Search

The creation of Exclusive Economic Zones (EEZs) in 1982 gave coastal countries sovereignty over their local tuna resources, whereas the migratory nature of tuna calls for regional management. However, as regional tuna management by Regional Fisheries Management Organisations (RFMOs) does not always facilitate optimal management of local resources by coastal countries, there is a need for an approach that ensures both the achievement of regional management objectives and optimisation of local benefits, i.e., "glocalised" management. To promote "glocal" management measures for the local populations of highly migratory species, (1) the spatio-temporal VAST model was used to estimate abundance indices for the adult regional Eastern Atlantic yellowfin tuna population and its local component in Ivorian waters using catch and effort data and (2) convergent cross mapping was used to examine the causal relationship between changes in abundance at these different spatial scales over time. Convergent cross-mapping detected a causal relationship between general stock dynamics and local dynamics, in the direction from global stock abundances to local resource abundances. This implies that the success of local fishing was closely linked to the general state of the stock. Conversely, we found no evidence of a causal relationship in the direction from local resources to the regional stock. This suggests that local adult dynamics had little or no influence on overall stock dynamics. Based on these results, we propose several criteria to ensure fairer distribution of tuna resources between coastal states and distant water fleets (DWFs).

The creation of Exclusive Economic Zones (EEZs) in 1982 gave coastal countries sovereignty over their local tuna resources, whereas the migratory nature of tuna calls for regional management. However, as regional tuna management by Regional Fisheries Management Organisations (RFMOs) does not always facilitate optimal management of local resources by coastal countries, there is a need for an approach that ensures both the achievement of regional management objectives and optimisation of local benefits, i.e., "glocalised" management. To promote "glocal" management measures for the local populations of highly migratory species, (1) the spatio-temporal VAST model was used to estimate abundance indices for the adult regional Eastern Atlantic yellowfin tuna population and its local component in Ivorian waters using catch and effort data and (2) convergent cross mapping was used to examine the causal relationship between changes in abundance at these different spatial scales over time. Convergent cross-mapping detected a causal relationship between general stock dynamics and local dynamics, in the direction from global stock abundances to local resource abundances. This implies that the success of local fishing was closely linked to the general state of the stock. Conversely, we found no evidence of a causal relationship in the direction from local resources to the regional stock. This suggests that local adult dynamics had little or no influence on overall stock dynamics. Based on these results, we propose several criteria to ensure fairer distribution of tuna resources between coastal states and distant water fleets (DWFs).

Anderson et al.’s 2019 paper ‘Close Kin Proximity in Yellowfin Tuna (Thunnus albacares) as a Driver of Population Genetic Structure in the Tropical Western and Central Pacific’ provided observations of genetically related individuals among sampled yellowfin tuna. Resampling of some individuals from the original study produced very different sequencing results when compared with the original dataset, one possible explanation of which is cross-contamination among the original samples. Re-analyses produced no indication of strong population structure, including a very slightly and consistent heterozygosity deficit with only one statistically significant pairwise FST value of 0.002. We identified only one pair of genetically similar individuals that could still be an artefact of lingering contamination. These new results therefore support a highly connected population of yellowfin tuna in the study area, although we do not rule out the potential for local adaptation driven by non-observed loci or genetic sub-structure operating at more contemporary scales.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

Yellowfin tuna of the Indian Ocean is overfished, and a better understanding of the stock structure is needed to enable sustainable management. Here, otolith δ18O values of young-of-the-year fish from known nursery areas of the equatorial Indian Ocean (West, Central and East) were used to establish a reference isotopic signature to predict the origin of sub-adult and adult individuals. Sub-adult tuna otolith δ18O values from Reunion Island were similar to the West nursery signature, but otolith δ18O values of sub-adults from Pakistan were unlike any of the nurseries sampled. Therefore, δ18O values from the Pakistan area samples were considered an additional nursery source for predicting the origin of adult tuna, using a multinomial logistic regression classification method. The western equatorial area was the most productive nursery for three fishing grounds sampled, with a minor contribution of Pakistan-like origin fish. Contribution of Central or East nurseries to the adult population was negligible. One adult otolith was analysed by secondary ion mass spectrometry along the otolith growth transect and results were compared with an isoscape approach to infer lifetime movements. This study is an important first step towards understanding the spatial structure and connectivity of the species

This paper presents an associative behavior-based abundance index (ABBI) providing direct estimates of the abundance of yellowfin tuna (Thunnus albacares) based on their associative behavior around floating objects (FOBs). Considering the associative dynamics of small yellowfin tuna individuals (<10 kg) at FOBs through residence and absence times at FOBs, together with acoustic data obtained from fisher’s echosounder buoys, the ABBI index is derived for yellowfin tuna in the western Indian Ocean over the period 2013-2019. This index accounts for both the FOB-associated and free-swimming components of the tuna populations, as well as for the effects of increasing numbers of FOBs on each component.

Cortisol is recognized as a physiological indicator of stress in fish. However, this hormone is typically measured in plasma samples. In this study, cortisol content was evaluated for the first time in the scales of tropical tuna. The sample included 20 skipjack tuna (Katsuwonus pelamis) and 25 yellowfin tuna (Thunnus albacares) collected in the Atlantic (the Gulf of Guinea off the Ivory Coast) and the Indian Ocean (off Reunion Island), and their scales were analyzed using an ELISA test. The results indicated that on average, cortisol concentration (1) did not show any geographical pattern, (2) was independent of fish size, and (3) was significantly higher in skipjack (mean 4.75 ± 6.56 ng g−1) than in yellowfin (mean 1.65 ± 1.85 ng g−1), although the difference was mainly due to four skipjack individuals. Larger datasets would be needed to confirm any species difference in cortisol concentration. The particularly high cortisol concentration observed in four individuals may be due to fish from different schools, suggesting the need for future sampling from free-swimming schools to investigate intra- and inter-school variability in cortisol concentration. This study opens the door for future research, including the collection of scales on tagged individuals, to investigate the links between chronic stress and behavior in these species.

This paper presents an associative behavior-based abundance index (ABBI) providing direct estimates of the abundance of yellowfin tuna (Thunnus albacares) based on their associative behavior around floating objects (FOBs). Considering the associative dynamics of small yellowfin tuna individuals (<10 kg) at FOBs through residence and absence times at FOBs, together with acoustic data obtained from fisher’s echosounder buoys, the ABBI index is derived for yellowfin tuna in the western Indian Ocean over the period 2013-2019. This index accounts for both the FOB-associated and free-swimming components of the tuna populations, as well as for the effects of increasing numbers of FOBs on each component.

Skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna are the target species of tropical tuna fisheries in the Indian Ocean, with high commercial value in the international market. High fishing pressure over the past three decades has raised concerns about their sustainability. Understanding life history strategies and stock structure is essential to determine species resilience and how they might respond to exploitation. Here we provide a comprehensive review of available knowledge on the biology, ecology, and stock structure of tropical tuna species in the Indian Ocean. We describe the characteristics of Indian Ocean tropical tuna fisheries and synthesize skipjack, yellowfin, and bigeye tuna key life history attributes such as biogeography, trophic ecology, growth, and reproductive biology. In addition, we evaluate the available literature about their stock structure using different approaches such as analysis of fisheries data, genetic markers, otolith microchemistry and tagging, among others. Based on this review, we conclude that there is a clear lack of ocean basin-scale studies on skipjack, yellowfin and bigeye tuna life history, and that regional stock structure studies indicate that the panmictic population assumption of these stocks should be investigated further. Finally, we identify specific knowledge gaps that should be addressed with priority to ensure a sustainable and effective management of these species.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

We investigated the associative behavior of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye (T. obsesus) tuna within multi‐species aggregations associated with drifting fish aggregating devices (dFADs) in two different regions of the western Indian Ocean: the Mozambique Channel and the Seychelles, using acoustic telemetry. We documented the residence and absence times of tunas at two temporal scales (coarse and fine scale) and made comparisons between regions. A total of 56 tunas were tagged and released at 7 different dFADs (4 in the Mozambique Channel and 3 in the Seychelles) during four research cruises. We recorded the first observations of skipjack tuna making excursions of more than 24 hours away from dFADs before returning and confirmed findings of other studies showing that yellowfin tuna can make long excursions (4.07 days) before returning to their home dFADs. Combining both studied regions, average residence times were 7.59 days (min 0.03; max 16.49), 6.64 days (min 0.01; max 26.72), and 4.58 days (min 0.09; max 18.33) for bigeye, yellowfin, and skipjack tuna, respectively. Exponential models best fitted the residence times for all three tuna species, indicating time‐independent probabilities of departure from dFADs. For yellowfin tuna, at a coarse temporal scale, no regional differences were observed in the residence times. However, at a fine temporal scale, regional differences were apparent in both residence and absence times. This study provides new information on the associative behavior of tunas at dFADs in the Indian Ocean which is key to improving the science‐based management of dFADs.

This paper presents an associative behavior-based abundance index (ABBI) providing direct estimates of the abundance of yellowfin tuna (Thunnus albacares) based on their associative behavior around floating objects (FOBs). Considering the associative dynamics of small yellowfin tuna individuals (<10 kg) at FOBs through residence and absence times at FOBs, together with acoustic data obtained from fisher’s echosounder buoys, the ABBI index is derived for yellowfin tuna in the western Indian Ocean over the period 2013-2019. This index accounts for both the FOB-associated and free-swimming components of the tuna populations, as well as for the effects of increasing numbers of FOBs on each component.

Cortisol is recognized as a physiological indicator of stress in fish. However, this hormone is typically measured in plasma samples. In this study, cortisol content was evaluated for the first time in the scales of tropical tuna. The sample included 20 skipjack tuna (Katsuwonus pelamis) and 25 yellowfin tuna (Thunnus albacares) collected in the Atlantic (the Gulf of Guinea off the Ivory Coast) and the Indian Ocean (off Reunion Island), and their scales were analyzed using an ELISA test. The results indicated that on average, cortisol concentration (1) did not show any geographical pattern, (2) was independent of fish size, and (3) was significantly higher in skipjack (mean 4.75 ± 6.56 ng g−1) than in yellowfin (mean 1.65 ± 1.85 ng g−1), although the difference was mainly due to four skipjack individuals. Larger datasets would be needed to confirm any species difference in cortisol concentration. The particularly high cortisol concentration observed in four individuals may be due to fish from different schools, suggesting the need for future sampling from free-swimming schools to investigate intra- and inter-school variability in cortisol concentration. This study opens the door for future research, including the collection of scales on tagged individuals, to investigate the links between chronic stress and behavior in these species.

Cortisol is recognized as a physiological indicator of stress in fish. However, this hormone is typically measured in plasma samples. In this study, cortisol content was evaluated for the first time in the scales of tropical tuna. The sample included 20 skipjack tuna (Katsuwonus pelamis) and 25 yellowfin tuna (Thunnus albacares) collected in the Atlantic (the Gulf of Guinea off the Ivory Coast) and the Indian Ocean (off Reunion Island), and their scales were analyzed using an ELISA test. The results indicated that on average, cortisol concentration (1) did not show any geographical pattern, (2) was independent of fish size, and (3) was significantly higher in skipjack (mean 4.75 ± 6.56 ng g−1) than in yellowfin (mean 1.65 ± 1.85 ng g−1), although the difference was mainly due to four skipjack individuals. Larger datasets would be needed to confirm any species difference in cortisol concentration. The particularly high cortisol concentration observed in four individuals may be due to fish from different schools, suggesting the need for future sampling from free-swimming schools to investigate intra- and inter-school variability in cortisol concentration. This study opens the door for future research, including the collection of scales on tagged individuals, to investigate the links between chronic stress and behavior in these species.

This paper presents an associative behavior-based abundance index (ABBI) providing direct estimates of the abundance of yellowfin tuna (Thunnus albacares) based on their associative behavior around floating objects (FOBs). Considering the associative dynamics of small yellowfin tuna individuals (<10 kg) at FOBs through residence and absence times at FOBs, together with acoustic data obtained from fisher’s echosounder buoys, the ABBI index is derived for yellowfin tuna in the western Indian Ocean over the period 2013-2019. This index accounts for both the FOB-associated and free-swimming components of the tuna populations, as well as for the effects of increasing numbers of FOBs on each component.

We investigated the associative behavior of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye (T. obsesus) tuna within multi‐species aggregations associated with drifting fish aggregating devices (dFADs) in two different regions of the western Indian Ocean: the Mozambique Channel and the Seychelles, using acoustic telemetry. We documented the residence and absence times of tunas at two temporal scales (coarse and fine scale) and made comparisons between regions. A total of 56 tunas were tagged and released at 7 different dFADs (4 in the Mozambique Channel and 3 in the Seychelles) during four research cruises. We recorded the first observations of skipjack tuna making excursions of more than 24 hours away from dFADs before returning and confirmed findings of other studies showing that yellowfin tuna can make long excursions (4.07 days) before returning to their home dFADs. Combining both studied regions, average residence times were 7.59 days (min 0.03; max 16.49), 6.64 days (min 0.01; max 26.72), and 4.58 days (min 0.09; max 18.33) for bigeye, yellowfin, and skipjack tuna, respectively. Exponential models best fitted the residence times for all three tuna species, indicating time‐independent probabilities of departure from dFADs. For yellowfin tuna, at a coarse temporal scale, no regional differences were observed in the residence times. However, at a fine temporal scale, regional differences were apparent in both residence and absence times. This study provides new information on the associative behavior of tunas at dFADs in the Indian Ocean which is key to improving the science‐based management of dFADs.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

How the size of female yellowfin tuna (Thunnus albacares) affects their spawning capability and fecundity is still an open and unresolved question due to the difficulties in investigating these complex effects in highly migratory pelagic marine fish species. However, this information is key to understanding the reproductive potential and resilience of the stock. We investigate how energetic resources are allocated for reproduction by female yellowfin tuna according to their size in the Gulf of Guinea (central-eastern Atlantic Ocean). Our results reveal that larger females have not only larger ovaries by virtue of their greater abdominal cavity, but also different fatty acid profiles in the gonads compared to smaller females, with potential effects on their spawning and recruitment patterns. This study contributes to the knowledge of size-dependent variation in female yellowfin tuna and paves the way for future studies on size-dependent effects on reproductive parameters in this species.

The Isla del Coco National Park, located on the Pacific coast of Costa Rica, is rich in biodiversity and has a high concentration of pelagic species. This high marine biodiversity makes the Isla del Coco National Park (PNIC) a very attractive place for illegal fishers. We analyzed a dataset covering 8 years (2003–2010) of patrol records from PNIC with the aim of determining, a) the spatial-temporal distribution of illegal fishing, b) other areas that could be prone to illegal fishing but are currently undetected, c) the most profitable areas for this activity and d) the economic trade-offs of this illegal activity in relation to potential gains and the costs. Residuals Autocovariate Generalized Additive Models (RAC-GAMs) were used to model the illegal fishing activity's spatial distribution in relation to topographic, biological and temporal (quarter of the year) variables. The final RAC-GAM showed that bathymetry, distance from the coast, slope of the seabed, and yellowfin tuna and silky shark abundance were the most important predictors of this activity. Predictive maps suggest a major trend in the abundance of illegal fishing between the second and third quarters of the year in waters surrounding a seamount within the Park. Maps of the most profitable areas highlighted a specific risk location that should be intensively monitored. Overall, the potential gains from this activity outweigh the potential costs of being caught. Our findings provide useful information that can be used to optimize enforcement, deter illegal fishing and, consequently, increasing the conservation of the protected species.

How the size of female yellowfin tuna (Thunnus albacares) affects their spawning capability and fecundity is still an open and unresolved question due to the difficulties in investigating these complex effects in highly migratory pelagic marine fish species. However, this information is key to understanding the reproductive potential and resilience of the stock. We investigate how energetic resources are allocated for reproduction by female yellowfin tuna according to their size in the Gulf of Guinea (central-eastern Atlantic Ocean). Our results reveal that larger females have not only larger ovaries by virtue of their greater abdominal cavity, but also different fatty acid profiles in the gonads compared to smaller females, with potential effects on their spawning and recruitment patterns. This study contributes to the knowledge of size-dependent variation in female yellowfin tuna and paves the way for future studies on size-dependent effects on reproductive parameters in this species.

How the size of female yellowfin tuna (Thunnus albacares) affects their spawning capability and fecundity is still an open and unresolved question due to the difficulties in investigating these complex effects in highly migratory pelagic marine fish species. However, this information is key to understanding the reproductive potential and resilience of the stock. We investigate how energetic resources are allocated for reproduction by female yellowfin tuna according to their size in the Gulf of Guinea (central-eastern Atlantic Ocean). Our results reveal that larger females have not only larger ovaries by virtue of their greater abdominal cavity, but also different fatty acid profiles in the gonads compared to smaller females, with potential effects on their spawning and recruitment patterns. This study contributes to the knowledge of size-dependent variation in female yellowfin tuna and paves the way for future studies on size-dependent effects on reproductive parameters in this species.

The yellowfin tuna (Thunnus albacares) (YFT) is among the eight marine species with the highest catches globally. The Spanish purse seine freezer fleet operating in the Indian Ocean is one of the most important YFT fishing fleets in the world. The South Oscillation Index (SOI), Pacific Decadal Oscillation (PDO), and Indian Ocean Dipole (IOD) are interrelated, and have combined effects in the Indian Ocean. Moreover, Madden–Julian Oscillation (MJO) is the dominant component of intraseasonal variability in the tropical Indian and Pacific oceans where the sea surface is warm. The main aim of present study is to understand the effect of these four climatic oscillations on Spanish purse seine YFT catches in the Indian Ocean. The ultimate goal is to estimate the specific time lag of the effect of each climatic oscillation on the YFT catches for management purposes. To estimate this, we adjusted different General Additive Models between the response variable (corrected YFT catches per unit of effort per year), compared to a combination of SOI, PDO, IOD, and MJO lagged up to 8 years. Our results suggest that there is a lagged effect modulated mainly by PDO-SOI, which could be related to a good recruitment, larval survival, or improved spawning. Thus, negative PDO phase (or positive SOI phase) lagged between 3 and 6 years could favor future stock abundance, while positive PDO phase (or negative SOI phase) lagged 3 or 6 years could negatively affect future stock abundance.

The Isla del Coco National Park, located on the Pacific coast of Costa Rica, is rich in biodiversity and has a high concentration of pelagic species. This high marine biodiversity makes the Isla del Coco National Park (PNIC) a very attractive place for illegal fishers. We analyzed a dataset covering 8 years (2003–2010) of patrol records from PNIC with the aim of determining, a) the spatial-temporal distribution of illegal fishing, b) other areas that could be prone to illegal fishing but are currently undetected, c) the most profitable areas for this activity and d) the economic trade-offs of this illegal activity in relation to potential gains and the costs. Residuals Autocovariate Generalized Additive Models (RAC-GAMs) were used to model the illegal fishing activity's spatial distribution in relation to topographic, biological and temporal (quarter of the year) variables. The final RAC-GAM showed that bathymetry, distance from the coast, slope of the seabed, and yellowfin tuna and silky shark abundance were the most important predictors of this activity. Predictive maps suggest a major trend in the abundance of illegal fishing between the second and third quarters of the year in waters surrounding a seamount within the Park. Maps of the most profitable areas highlighted a specific risk location that should be intensively monitored. Overall, the potential gains from this activity outweigh the potential costs of being caught. Our findings provide useful information that can be used to optimize enforcement, deter illegal fishing and, consequently, increasing the conservation of the protected species.

The Isla del Coco National Park, located on the Pacific coast of Costa Rica, is rich in biodiversity and has a high concentration of pelagic species. This high marine biodiversity makes the Isla del Coco National Park (PNIC) a very attractive place for illegal fishers. We analyzed a dataset covering 8 years (2003–2010) of patrol records from PNIC with the aim of determining, a) the spatial-temporal distribution of illegal fishing, b) other areas that could be prone to illegal fishing but are currently undetected, c) the most profitable areas for this activity and d) the economic trade-offs of this illegal activity in relation to potential gains and the costs. Residuals Autocovariate Generalized Additive Models (RAC-GAMs) were used to model the illegal fishing activity's spatial distribution in relation to topographic, biological and temporal (quarter of the year) variables. The final RAC-GAM showed that bathymetry, distance from the coast, slope of the seabed, and yellowfin tuna and silky shark abundance were the most important predictors of this activity. Predictive maps suggest a major trend in the abundance of illegal fishing between the second and third quarters of the year in waters surrounding a seamount within the Park. Maps of the most profitable areas highlighted a specific risk location that should be intensively monitored. Overall, the potential gains from this activity outweigh the potential costs of being caught. Our findings provide useful information that can be used to optimize enforcement, deter illegal fishing and, consequently, increasing the conservation of the protected species.

Otolith chemistry of young-of-year (YOY) yellowfin tuna Thunnus albacares was examined to determine whether chemical signatures are distinct across major spawning areas in the Atlantic Ocean. YOY yellowfin tuna otoliths were collected from 4 locations in the Atlantic Ocean (Gulf of Mexico, Caribbean Sea, Cape Verde, and Gulf of Guinea) from 2013-2015, and trace element (Li, Mg, Mn, Sr, Zn, and Ba) and stable isotope (delta C-13 and delta O-18) analyses were conducted to investigate regional variation in otolith chemical composition. Results indicated that significant regional differences in chemical signatures existed for each cohort of YOY yellowfin tuna investigated. Quadratic discriminant function analysis showed that nursery assignment accuracies based on otolith trace elements and stable isotopes were 64-85% for each cohort, justifying the use of these natural tracers as regional discriminators for yellowfin tuna. Significant interannual variability in regional signatures was also detected, highlighting the importance of age-class matching when using the baseline of nursery signatures to estimate the origin of sub-adult and adult yellowfin tuna. This study clearly demonstrates that baseline chemical signatures in the otoliths of YOY yellowfin tuna are distinct and can therefore serve as an effective tool for assigning older individuals to their nursery of origin, ultimately providing a way to improve our understanding of the population connectivity and mixing rates of this species in the Atlantic Ocean.

Otolith chemistry of young-of-year (YOY) yellowfin tuna Thunnus albacares was examined to determine whether chemical signatures are distinct across major spawning areas in the Atlantic Ocean. YOY yellowfin tuna otoliths were collected from 4 locations in the Atlantic Ocean (Gulf of Mexico, Caribbean Sea, Cape Verde, and Gulf of Guinea) from 2013-2015, and trace element (Li, Mg, Mn, Sr, Zn, and Ba) and stable isotope (delta C-13 and delta O-18) analyses were conducted to investigate regional variation in otolith chemical composition. Results indicated that significant regional differences in chemical signatures existed for each cohort of YOY yellowfin tuna investigated. Quadratic discriminant function analysis showed that nursery assignment accuracies based on otolith trace elements and stable isotopes were 64-85% for each cohort, justifying the use of these natural tracers as regional discriminators for yellowfin tuna. Significant interannual variability in regional signatures was also detected, highlighting the importance of age-class matching when using the baseline of nursery signatures to estimate the origin of sub-adult and adult yellowfin tuna. This study clearly demonstrates that baseline chemical signatures in the otoliths of YOY yellowfin tuna are distinct and can therefore serve as an effective tool for assigning older individuals to their nursery of origin, ultimately providing a way to improve our understanding of the population connectivity and mixing rates of this species in the Atlantic Ocean.

Moored fish aggregating devices (MFADs) are increasingly being used in small-scale tropical fisheries to access pelagic fish species that are otherwise difficult to harvest in large numbers. Little attention has yet been paid to monitoring MFADs in coastal areas, however. This is most likely due to the small-scale nature of most fisheries that utilize them and the presumed lower impact of those fisheries on fish stocks and their ecosystems. In this paper, we examined the abundance and density of MFADs around Guadeloupe, using aerial line transect surveys. Estimated MFAD densities were found to be high compared with previously reported densities in this area, especially within the 22–45 km range offshore. We examine and discuss possible reasons for these high densities. The main drivers appear to be the target species dolphinfish (Coryphaena hippurus) and yellowfin tuna (Thunnus albacares) and related fishing behaviour. We present different approaches for reducing and monitoring MFADs densities, including the co-management of MFAD territorial use rights by fishing communities.

Moored fish aggregating devices (MFADs) are increasingly being used in small-scale tropical fisheries to access pelagic fish species that are otherwise difficult to harvest in large numbers. Little attention has yet been paid to monitoring MFADs in coastal areas, however. This is most likely due to the small-scale nature of most fisheries that utilize them and the presumed lower impact of those fisheries on fish stocks and their ecosystems. In this paper, we examined the abundance and density of MFADs around Guadeloupe, using aerial line transect surveys. Estimated MFAD densities were found to be high compared with previously reported densities in this area, especially within the 22–45 km range offshore. We examine and discuss possible reasons for these high densities. The main drivers appear to be the target species dolphinfish (Coryphaena hippurus) and yellowfin tuna (Thunnus albacares) and related fishing behaviour. We present different approaches for reducing and monitoring MFADs densities, including the co-management of MFAD territorial use rights by fishing communities.

Moored fish aggregating devices (MFADs) are increasingly being used in small-scale tropical fisheries to access pelagic fish species that are otherwise difficult to harvest in large numbers. Little attention has yet been paid to monitoring MFADs in coastal areas, however. This is most likely due to the small-scale nature of most fisheries that utilize them and the presumed lower impact of those fisheries on fish stocks and their ecosystems. In this paper, we examined the abundance and density of MFADs around Guadeloupe, using aerial line transect surveys. Estimated MFAD densities were found to be high compared with previously reported densities in this area, especially within the 22–45 km range offshore. We examine and discuss possible reasons for these high densities. The main drivers appear to be the target species dolphinfish (Coryphaena hippurus) and yellowfin tuna (Thunnus albacares) and related fishing behaviour. We present different approaches for reducing and monitoring MFADs densities, including the co-management of MFAD territorial use rights by fishing communities.

This study was conducted in the lagoon of Mischief Reef, South China Sea to test the feasibility of feeding and rearing wild caught yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis juveniles in small, deep sea-water, cages. Fish started active feeding four days after transfer to the rearing cage. Initial feeding depth between yellowfin tuna and skipjack tuna was not significantly different (P > 0.05). The initial feeding depth for yellowfin tuna juveniles was 2.97±1.09 m, and skipjack tuna fed at 2.95 ± 0.77 m. After the 30 day rearing experiment specific growth rates of yellowfin tuna and skipjack tuna were: 0.25 ± 0.02 %/day and 0.32 ± 0.03%/day, respectively; survival rate of yellowfin tuna was 100%, and the survival rate of skipjack tuna was 82.6%. The estimated feed conversion ratio was 9.73 in this study. The results of this study provide practical data for culturing wild caught yellowfin tuna and skipjack tuna juveniles in sea cages.

Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival curves with the objective of determining the behavioral dynamics of fish joining and leaving the FADs. Residence times at FADs were characterized by 4 behavioral modes: briefly passing near a FAD (average 13.1 min), short association (average 2.9 d), and 2 long association behaviors (13.8 and 23.2 d, respectively). Statistical analyses suggest that different behavioral modes were likely dependent upon local conditions around the FAD at a given time (environmental factors or social interactions). We observed 2 behavioral modes for absence times from FADs: short (2.8 d) and long (infinite). More importantly, individuals exhibited behavioral variability, switching between short and long residence times at FADs. This suggests that large pelagic fish can display a range of behavioral responses while in an array of FADs, challenging the common hypothesis of a single behavioral pattern, which could ultimately lead to an ecological trap. Survival curves were best fitted with exponential models, suggesting that underlying behavioral processes were time independent.

Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival curves with the objective of determining the behavioral dynamics of fish joining and leaving the FADs. Residence times at FADs were characterized by 4 behavioral modes: briefly passing near a FAD (average 13.1 min), short association (average 2.9 d), and 2 long association behaviors (13.8 and 23.2 d, respectively). Statistical analyses suggest that different behavioral modes were likely dependent upon local conditions around the FAD at a given time (environmental factors or social interactions). We observed 2 behavioral modes for absence times from FADs: short (2.8 d) and long (infinite). More importantly, individuals exhibited behavioral variability, switching between short and long residence times at FADs. This suggests that large pelagic fish can display a range of behavioral responses while in an array of FADs, challenging the common hypothesis of a single behavioral pattern, which could ultimately lead to an ecological trap. Survival curves were best fitted with exponential models, suggesting that underlying behavioral processes were time independent. © Inter-Research 2013., SCOPUS: ar.j, info:eu-repo/semantics/published

Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival curves with the objective of determining the behavioral dynamics of fish joining and leaving the FADs. Residence times at FADs were characterized by 4 behavioral modes: briefly passing near a FAD (average 13.1 min), short association (average 2.9 d), and 2 long association behaviors (13.8 and 23.2 d, respectively). Statistical analyses suggest that different behavioral modes were likely dependent upon local conditions around the FAD at a given time (environmental factors or social interactions). We observed 2 behavioral modes for absence times from FADs: short (2.8 d) and long (infinite). More importantly, individuals exhibited behavioral variability, switching between short and long residence times at FADs. This suggests that large pelagic fish can display a range of behavioral responses while in an array of FADs, challenging the common hypothesis of a single behavioral pattern, which could ultimately lead to an ecological trap. Survival curves were best fitted with exponential models, suggesting that underlying behavioral processes were time independent.

Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival curves with the objective of determining the behavioral dynamics of fish joining and leaving the FADs. Residence times at FADs were characterized by 4 behavioral modes: briefly passing near a FAD (average 13.1 min), short association (average 2.9 d), and 2 long association behaviors (13.8 and 23.2 d, respectively). Statistical analyses suggest that different behavioral modes were likely dependent upon local conditions around the FAD at a given time (environmental factors or social interactions). We observed 2 behavioral modes for absence times from FADs: short (2.8 d) and long (infinite). More importantly, individuals exhibited behavioral variability, switching between short and long residence times at FADs. This suggests that large pelagic fish can display a range of behavioral responses while in an array of FADs, challenging the common hypothesis of a single behavioral pattern, which could ultimately lead to an ecological trap. Survival curves were best fitted with exponential models, suggesting that underlying behavioral processes were time independent.

Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival curves with the objective of determining the behavioral dynamics of fish joining and leaving the FADs. Residence times at FADs were characterized by 4 behavioral modes: briefly passing near a FAD (average 13.1 min), short association (average 2.9 d), and 2 long association behaviors (13.8 and 23.2 d, respectively). Statistical analyses suggest that different behavioral modes were likely dependent upon local conditions around the FAD at a given time (environmental factors or social interactions). We observed 2 behavioral modes for absence times from FADs: short (2.8 d) and long (infinite). More importantly, individuals exhibited behavioral variability, switching between short and long residence times at FADs. This suggests that large pelagic fish can display a range of behavioral responses while in an array of FADs, challenging the common hypothesis of a single behavioral pattern, which could ultimately lead to an ecological trap. Survival curves were best fitted with exponential models, suggesting that underlying behavioral processes were time independent. © Inter-Research 2013., SCOPUS: ar.j, info:eu-repo/semantics/published

Tuna are the major marine fishery in Sri Lanka, and yellowfin tuna (YFT) (Thunnus albacares) and skipjack tuna (SJT) (Katsuwonus pelamis) represent 94% of all tuna caught. The tuna catch in Sri Lanka has increased rapidly over recent years and this is true generally for the Indian Ocean. Tuna are a major animal protein source for 20 million people in Sri Lanka, while marine fisheries provide the main income source for most Sri Lankan coastal communities. While the importance of the fishery will require effective stock management practices to be employed, to date no genetic studies have been undertaken to assess wild stock structure in Sri Lankan waters as a basis for developing effective stock management practices for tuna in the future. This thesis undertook such a genetic analysis of Sri Lankan T. albacares and K. pelamis stocks. Samples of both YFT and SJT were collected over four years (2001 - 2004) from seven fishing grounds around Sri Lanka, and also from the Laccadive and Maldive Islands in the western Indian Ocean. Partial mitochondrial DNA (mtDNA) ATPase 6 and 8 genes and nuclear DNA (nDNA) microsatellite variation were examined for relatively large samples of each species to document genetic diversity within and among sampled sites and hence to infer stock structure and dispersal behaviour. Data for YFT showed significant genetic differentiation for mtDNA only among specific sites and hence provided some evidence for spatial genetic structure. Spatial Analysis of Molecular Variance (SAMOVA) analysis suggests that three geographically meaningful YFT groups are present. Specifically, one group comprising a single site on the Sri Lankan west coast, a second group comprising a single site on the east coast and a third group of remaining sites around Sri Lanka and the Maldive Islands. Patterns of variation at nDNA loci in contrast, indicate extensive contemporary gene flow among all sites and reflect very large population sizes. For SJT, both mtDNA and nDNA dat

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the Surface mixed layer above the thermocline and it has been Suggested that they are physiologically restricted to water lerriperatt.11-CS no more than 8 degrees C colder than Surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near ail anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with all internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 in (maximum thermocline depth experienced by the fish) but, over the Course of the track, it performed three deep dives to 578 in, 982 In and 1160 In. Minimum ambient water temperatures recorded Lit these depths were 8.6 degrees C, 7.4 degrees C and 5.9 degrees C respectively and varied by up to 23.3 degrees C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 degrees C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15- 16 degrees C) and of temperatures of the gut cavity (mode at 6 degrees C). The reason for these dives call not be known. These depths and temperatures significantly exceed those reported ill the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the Surface mixed layer above the thermocline and it has been Suggested that they are physiologically restricted to water lerriperatt.11-CS no more than 8 degrees C colder than Surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near ail anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with all internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 in (maximum thermocline depth experienced by the fish) but, over the Course of the track, it performed three deep dives to 578 in, 982 In and 1160 In. Minimum ambient water temperatures recorded Lit these depths were 8.6 degrees C, 7.4 degrees C and 5.9 degrees C respectively and varied by up to 23.3 degrees C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 degrees C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15- 16 degrees C) and of temperatures of the gut cavity (mode at 6 degrees C). The reason for these dives call not be known. These depths and temperatures significantly exceed those reported ill the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the Surface mixed layer above the thermocline and it has been Suggested that they are physiologically restricted to water lerriperatt.11-CS no more than 8 degrees C colder than Surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near ail anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with all internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 in (maximum thermocline depth experienced by the fish) but, over the Course of the track, it performed three deep dives to 578 in, 982 In and 1160 In. Minimum ambient water temperatures recorded Lit these depths were 8.6 degrees C, 7.4 degrees C and 5.9 degrees C respectively and varied by up to 23.3 degrees C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 degrees C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15- 16 degrees C) and of temperatures of the gut cavity (mode at 6 degrees C). The reason for these dives call not be known. These depths and temperatures significantly exceed those reported ill the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

This dissertation addressed questions related to the selective advantages of regional endothermy and its independent evolution among several fish groups. The chapters integrate laboratory and field physiological measurements to provide a better understanding ofthe evolution of regional endothermy and its importance as an adaptation to the pelagic environment. Studies on the swimming energetics of the eastern Pacific bonito (Sarda chiliensis) revealed that the bonito had a similar cost of transport to that of similar sized yellowfin tuna (Thunnus albacares) and that the bonito had a significantly lower standard metabolic rate than tuna. Thermal studies on live slender tuna, Allothunnus fallai, were the first to document both red muscle (RM) and eye and brain endothermy for this species and establish regional endothermy as a synapomorphy of the Tribe Thunnini. Additional findings for A.fallai revealed this species to possess a brain heater, a thermogenic organ composed of portions of all four of the rectus muscles. These findings demonstrate that the use of a heater tissue to elevate cranial temperatures has evolved independently in at least three fish groups.Movement studies on the mako shark (Isurus oxyrinchus) used acoustic telemetry to record the in-vivo stomach temperatures and depth distribution off the coast of Southern California. This work showed that the tracked makos remained in the upper 12 m of the water column during up to 80% of the track period and that larger makos dove to greater depths. Stomach temperature data were recorded for all tracked makos (including young of the year), and these data were used to document feeding events in five of the seven tracking sessions.A study on the muscle morphology of three thresher shark species (common thresher, Alopias vulpinus, pelagic thresher, A. pelagicus, and bigeye thresher, A. superciliosus) revealed interspecific differences in the RM transverse position and distribution along the body. The common threshe

This dissertation addressed questions related to the selective advantages of regional endothermy and its independent evolution among several fish groups. The chapters integrate laboratory and field physiological measurements to provide a better understanding ofthe evolution of regional endothermy and its importance as an adaptation to the pelagic environment. Studies on the swimming energetics of the eastern Pacific bonito (Sarda chiliensis) revealed that the bonito had a similar cost of transport to that of similar sized yellowfin tuna (Thunnus albacares) and that the bonito had a significantly lower standard metabolic rate than tuna. Thermal studies on live slender tuna, Allothunnus fallai, were the first to document both red muscle (RM) and eye and brain endothermy for this species and establish regional endothermy as a synapomorphy of the Tribe Thunnini. Additional findings for A.fallai revealed this species to possess a brain heater, a thermogenic organ composed of portions of all four of the rectus muscles. These findings demonstrate that the use of a heater tissue to elevate cranial temperatures has evolved independently in at least three fish groups.Movement studies on the mako shark (Isurus oxyrinchus) used acoustic telemetry to record the in-vivo stomach temperatures and depth distribution off the coast of Southern California. This work showed that the tracked makos remained in the upper 12 m of the water column during up to 80% of the track period and that larger makos dove to greater depths. Stomach temperature data were recorded for all tracked makos (including young of the year), and these data were used to document feeding events in five of the seven tracking sessions.A study on the muscle morphology of three thresher shark species (common thresher, Alopias vulpinus, pelagic thresher, A. pelagicus, and bigeye thresher, A. superciliosus) revealed interspecific differences in the RM transverse position and distribution along the body. The common threshe

A Bayesian integrated population dynamics model to analyze data for protected species.� Managing wildlife�human interactions demands reliable information about the likely consequences of management actions. This requirement is a general one, whatever the taxonomic group. We describe a method for estimating population dynamics and decision analysis that is generally applicable, extremely flexible, uses data efficiently, and gives answers in a useful format. Our case study involves bycatch of a protected species, the Northeastern Offshore Spotted Dolphin (Stenella attenuata), in the tuna fishery of the eastern Pacific Ocean. Informed decision�making requires quantitative analyses taking all relevant information into account, assessing how bycatch affects these species and how regulations affect the fisheries, and describing the uncertainty in analyses. Bayesian analysis is an ideal framework for delivering information on uncertainty to the decision�making process. It also allows information from other populations or species or expert judgment to be included in the analysis, if appropriate. Integrated analysis attempts to include all relevant data for a population into one analysis by combining analyses, sharing parameters, and simultaneously estimating all parameters, using a combined objective function. It ensures that model assumptions and parameter estimates are consistent throughout the analysis, that uncertainty is propagated through the analysis, and that the correlations among parameters are preserved. Perhaps the most important aspect of integrated analysis is the way it both enables and forces consideration of the system as a whole, so that inconsistencies can be observed and resolved., Modelo bayesiano integrado de dinámica de poblaciones para el análisis de datos de especies protegidas.¿ La gestión de las interacciones que se producen entre la flora y fauna y los seres humanos requiere disponer de información fiable acerca de las consecuencias probables que generarán las acciones de gestión. Este requisito es de carácter general, con independencia del grupo taxonómico. En el presente artículo describimos un método para estimar parámetros de dinámica de poblaciones y de toma de decisiones, de aplicación general, extremadamente flexible, que utiliza datos de un modo eficiente y proporciona respuestas en un formato útil. Nuestro ejemplo está relacionado con la captura accidental de una especie protegida, el delfín moteado (Stenella attenuata), en las pesquerías de atún de la costa este del océano Pacífico. Una toma de decisiones bien fundamentada requiere disponer de análisis cuantitativos que tomen en consideración toda la información relevante, permitiendo evaluar cómo afecta la captura accidental a estas especies y cómo afecta la normativa a las pesquerías, además de describir la incertidumbre en los análisis. El análisis bayesiano constituye un marco idóneo para proporcionar información sobre la incertidumbre que acompaña al proceso de toma de decisiones. Además de ser adecuado, permite incluir información acerca de otras poblaciones o especies en los análisis, así como un criterio experto. El análisis integrado pretende incluir en un único proceso todos los datos relevantes de una población, combinando análisis, compartiendo parámetros y estimando el conjunto de dichos parámetros de forma simultánea mediante el empleo de una función objetiva combinada. También garantiza que las presuposiciones del modelo y las estimaciones de parámetros sean coherentes a lo largo de todo el análisis, que la incertidumbre se transmita a través del mismo, y que se mantengan las correlaciones entre los distintos parámetros. Quizá el aspecto más relevante del análi

This research project was undertaken on two species of tropical tuna: the yellowfin Thunnus albacares and the skipjack Katsuwonus pelamis, to explore the dynamic physiological design features of tunas which underly the highly-developed thunniform propulsion mechanism. To achieve an integrated understanding of tuna swimming mechanics, a combination of electromyography, kinematics, and direct force measurements was used to probe the dynamic function of the myotomal red muscle as fish swam over a range of sustained, aerobic swimming speeds in a large water tunnel.In both species, onset of red muscle activation proceeds sequentially in a rostra-caudal direction, while deactivation is nearly simultaneous at all sites, coincident with peak force in the caudal tendons. In yellowfin, there is complete segregation of contralateral activity, while in skipjack there is slight overlap. In both species, all red muscle on one side is active simultaneously for part of each cycle. Comparison with other fish species shows that the tuna EMG patterns culminate a spectrum of activation patterns underlying swimming modes from anguilliform to thunniform.Coupling kinematics with EMG data revealed that muscle activation occurs after the midline has reached its maximum convexity at any given axial location; therefore, it was concluded that midline curvature is not an accurate indicator of local strain in the myotomal cone muscle. Activation and curvature waves travel down the body at the same rate, so muscle function is predicted not to vary by axial location. In yellowfin, peak force occurs in the caudal tendons as the tail tip crosses the midpoint of its sweep; in skipjack, when the tip is about three-quarters through its sweep.Internal force measurements were made for the first time in any fish species by fitting a stainless steel buckle force transducer around the pair of deep caudal tendons on one side. At cruising speeds, mean forces were 1.3-3.8 N in yellowfin and 1.6-4.1 N in skipja

This research project was undertaken on two species of tropical tuna: the yellowfin Thunnus albacares and the skipjack Katsuwonus pelamis, to explore the dynamic physiological design features of tunas which underly the highly-developed thunniform propulsion mechanism. To achieve an integrated understanding of tuna swimming mechanics, a combination of electromyography, kinematics, and direct force measurements was used to probe the dynamic function of the myotomal red muscle as fish swam over a range of sustained, aerobic swimming speeds in a large water tunnel.In both species, onset of red muscle activation proceeds sequentially in a rostra-caudal direction, while deactivation is nearly simultaneous at all sites, coincident with peak force in the caudal tendons. In yellowfin, there is complete segregation of contralateral activity, while in skipjack there is slight overlap. In both species, all red muscle on one side is active simultaneously for part of each cycle. Comparison with other fish species shows that the tuna EMG patterns culminate a spectrum of activation patterns underlying swimming modes from anguilliform to thunniform.Coupling kinematics with EMG data revealed that muscle activation occurs after the midline has reached its maximum convexity at any given axial location; therefore, it was concluded that midline curvature is not an accurate indicator of local strain in the myotomal cone muscle. Activation and curvature waves travel down the body at the same rate, so muscle function is predicted not to vary by axial location. In yellowfin, peak force occurs in the caudal tendons as the tail tip crosses the midpoint of its sweep; in skipjack, when the tip is about three-quarters through its sweep.Internal force measurements were made for the first time in any fish species by fitting a stainless steel buckle force transducer around the pair of deep caudal tendons on one side. At cruising speeds, mean forces were 1.3-3.8 N in yellowfin and 1.6-4.1 N in skipja

Oxygen transport and cardiovascular responses to exercise and environmental changes were studied in swimming yellowfin tuna (Thunnus albacares). a high­ performance teleost. Use of a large water tunnel permitted measurements of heart rate (fH), relative stroke volume (SV), and arterial and venous blood-gas variables during increases in swimming velocity or rapid changes in ambient temperature and oxygen content that simulated vertical migrations through the thermocline.In addition. a model of aerobic swimming performance for a 50 cm yellowfin was developed, based on the oxygen delivery potential of the cardiovascular system, and oxygen demand during swimming. This model predicts a lower maximal sustained (aerobic) velocity (~3-4 fork lengths [FL]/s) compared to previous estimates. This model also predicts that the rate of total oxygen consumption is not maximal at the maximal sustained velocity, suggesting that additional aerobic scope is available for other high­ oxygen demand metabolic functions (e.g., digestion. oxygen debt recovery, and growth).Measured FHs, although highly variable among individuals, were generally lower than previously reported, averaging from 68 to 102 bpm with a velocity increase from 1.0 to 2.9 FL/s. These FHs are comparable to other active teleosts at similar velocities. A significant bradycardia developed at an oxygen tension of 16.1 kPa O2, and fH was very sensitive to changes in temperature (Q10 = 2.37, 28°C to l8°C).Relative SV measurements revealed a slight decrease with exercise (mean 3.9%), indicating that, unlike most other fishes, cardiac output in the yellowfin is regulated primarily through changes in fH. However, SV increased with a drop in temperature, moderating the effect of fH on cardiac output (Q10 = 1.52).Yellowfin blood has a high-oxygen carrying capacity (16 to 18 ml O2/dl) and a low in vivo oxygen affinity (P50 = 5.3 kPa). Exercise caused in rise in arterial (74 to 88%) and a decline in venous oxygen saturation (48 to

Oxygen transport and cardiovascular responses to exercise and environmental changes were studied in swimming yellowfin tuna (Thunnus albacares). a high­ performance teleost. Use of a large water tunnel permitted measurements of heart rate (fH), relative stroke volume (SV), and arterial and venous blood-gas variables during increases in swimming velocity or rapid changes in ambient temperature and oxygen content that simulated vertical migrations through the thermocline.In addition. a model of aerobic swimming performance for a 50 cm yellowfin was developed, based on the oxygen delivery potential of the cardiovascular system, and oxygen demand during swimming. This model predicts a lower maximal sustained (aerobic) velocity (~3-4 fork lengths [FL]/s) compared to previous estimates. This model also predicts that the rate of total oxygen consumption is not maximal at the maximal sustained velocity, suggesting that additional aerobic scope is available for other high­ oxygen demand metabolic functions (e.g., digestion. oxygen debt recovery, and growth).Measured FHs, although highly variable among individuals, were generally lower than previously reported, averaging from 68 to 102 bpm with a velocity increase from 1.0 to 2.9 FL/s. These FHs are comparable to other active teleosts at similar velocities. A significant bradycardia developed at an oxygen tension of 16.1 kPa O2, and fH was very sensitive to changes in temperature (Q10 = 2.37, 28°C to l8°C).Relative SV measurements revealed a slight decrease with exercise (mean 3.9%), indicating that, unlike most other fishes, cardiac output in the yellowfin is regulated primarily through changes in fH. However, SV increased with a drop in temperature, moderating the effect of fH on cardiac output (Q10 = 1.52).Yellowfin blood has a high-oxygen carrying capacity (16 to 18 ml O2/dl) and a low in vivo oxygen affinity (P50 = 5.3 kPa). Exercise caused in rise in arterial (74 to 88%) and a decline in venous oxygen saturation (48 to