Search

Climate change threatens fisheries health through changing ecosystem dynamics; however, the impacts on the physiology and ecology of commercial fish populations are unclear. Here, annually deposited growth increments of female yelloweye rockfish (Sebastes ruberrimus) opercula collected in the Gulf of Alaska were used to successfully reconstruct lifetime (∼1-year resolution) steroid hormone, stable isotope, spawning, and stress data. We assessed how hormone profiles, spawning and distress frequencies related to sea surface temperature (SST), chlorophyll a concentrations as well as climate indices. Further, we assessed whether incorporating indicators of foraging depth and diet, stable isotope values (ẟ13C and ẟ15N), would improve model interpretations. Progesterone and estradiol concentrations decreased with increasing SST, suggesting that increasing SSTs may negatively impact juvenile and subadult females' reproductive development. Spawning frequency was positively linked to changes in the North Pacific Gyre Oscillation (NPGO) index, potentially timed with favorable conditions for larval survival. This was supported by juveniles having a lower probability of a distress event during positive NPGO years compared to negative NPGO years. While relationships among environmental data and yelloweye rockfish physiology were weak, this study provides insight into the environmental impacts on the lifetime reproduction and stress of a commercially important teleost species. [ABSTRACT FROM AUTHOR]

Seismic airgun surveys to map petroleum deposits in the seabed may impact behaviour of marine animals over large distances. Understanding whether fish spawning behaviour is affected by this anthropogenic noise source is important because reproductive success may be impacted. The fine-scale behavioural responses of Atlantic cod to airgun exposure over an extended period were investigated using an acoustic telemetry positioning system on a spawning ground in Norway. During 2019 to 2021, 135 spawning cod were equipped with telemetry sensor tags and were exposed to airgun shooting during the spawning periods of 2020 and 2021, with varying received sound levels comparable to a full-scale survey at distances of 5 to >40 km. Cod demonstrated only weak responses to the disturbance from repeated 3-h treatment periods over 5-d, swimming on average slightly deeper during seismic exposure compared to silent control periods. This response varied between individuals. Longer-term effects of seismic exposure on swimming depth were not detected. No changes in swimming acceleration, displacement, or area use occurred. These results suggest that relatively distant seismic surveys do not substantially alter cod behaviour during the spawning period at received sound exposure levels varying between 115 and 145 dB re 1 µPa2s over a 5-d period. [ABSTRACT FROM AUTHOR]

This study used Spanish Kiko goats as a small ruminant model (SRM) for teaching animal science courses via experiential laboratory-based methods at a small liberal arts college in the Southeastern United State. Perceivably, the SRMs presents an accessible and sustainable teaching tool for undergraduate education at institutions with limited resources, such as cattle facilities. The use of mature (> 3 years old) bucks (male model 1, 2 & 3), does (female model 1 & 2), and kids (kid model 1, 2, 3; 8 months old) as SRMs in 4 courses and resultant learning is reported herein. SRMs were fed, late weaned, and continuously bred to simulate the nutritional and reproductive management practiced in rotationally grazed strictly forage-fed cattle. Growth performances amongst bucks (pre and post pubertal; Figure 1), does (pre- and post-partum Figure 2), and kids (pre and post weaning Figure 3) were recorded and analyzed. Feed intake trials (Figures 4 and 5), fecal analysis, and apparent DMD were conducted. The benefits of continuous suckling and postweaning management of does and kids were realized as 100% of does and kids successfully transited each breeding period. In addition, kids approached market weights (15.53 kg) at 136 days postpartum (Figure 3) and does were rebred at first postpartum estrus (62 days). The use of prebreeding season reproductive tract examinations via ultrasound and BSE in female and male SRMs enabled effective evaluations of the poor reproductive performance of the cattle herd (59.3% pregnancy rate in 2022). The use of SRMs allowed for learning ruminant gastrointestinal and reproductive system physiology. Subsequently, comprehension of the impact of mineral and vitamin deficiencies on the annually declining reproductive performance of rotationally grazed cattle was enhanced. Conclusively, the use of SRMs supported my learning and is recommended for teaching/learning in animal sciences at institutions with limited resources. [ABSTRACT FROM AUTHOR]

In species with limited opportunities for pre‐ejaculatory sexual selection (behavioural components), post‐ejaculatory mechanisms may provide opportunities for mate choice after gametes have been released. Recent evidence from a range of taxa has revealed that cryptic female choice (i.e., female‐mediated differential fertilization bias), through chemical cues released with or from eggs, can differentially regulate the swimming characteristics of sperm from various males and ultimately determine male fertilization success under sperm competition. We assessed the potential role that such female‐modulated chemical cues play in influencing sperm swimming characteristics in beach‐spawning capelin (Mallotus villosus), an externally fertilizing fish that mates as couples (one male and one female) or threesomes (two males and one female) with presumably limited opportunities for pre‐ejaculatory sexual selection. We assayed sperm swimming characteristics under varying doses and donor origins of egg cues and also examined the possibility of assortative mating based on body size. We found mating groups were not associated by size, larger males did not produce better quality ejaculates, and egg cues (regardless of dosage or donor identity) did not influence sperm swimming characteristics. Our findings suggest that intersexual pre‐ejaculatory sexual selection and cryptic female choice mediated by female chemical cues are poorly developed in capelin, possibly due to unique natural selection constraints on reproduction. [ABSTRACT FROM AUTHOR]

Stock assessments historically have used age- and size-independent methods to estimate reproductive output in marine fishes. Recent assessments have used total egg production (TEP), often assuming an invariant spawning frequency (SF) for all females. However, spawning parameters vary with age and size, which invalidates this assumption. This study investigated the age- and size-dependence of female spawning fraction, duration, and frequency in two economically valuable species, gag (Mycteroperca microlepis) and scamp (Mycteroperca phenax), in Atlantic waters off the southeastern United States, with the ultimate objective of quantifying the effect of these dependencies on TEP estimates. Spawning parameters had moderate-to-strong dome-shaped relationships with age and size (r 2 = 0.63–0.94), peaking at intermediate ages and sizes. As larger, older females approach sexual transition, they may increase their lifetime reproductive success by shifting energy resources away from female reproductive investment (i.e. eggs) towards investment that will promote future male reproductive success (i.e. gonad transformation). The estimate of TEP based on age-dependent SF was 38% lower for gag and 41% lower for scamp than the estimate based on age-independent (AI) SF; therefore, the AI method overestimates stock productivity. Incorporating age- and size-based reproductive data into assessments can lead to more reliable stock productivity estimates and potentially improved management. [ABSTRACT FROM AUTHOR]

Many marine fishes mate in massive and spectacular gatherings at predictable times and places. These spawning aggregations are often attractive targets of fisheries. Many commercially important fish species exhibit aggregation spawning, and many have undergone serious declines from overfishing. It is timely to explore whether the exploitation of spawning aggregations makes species particularly susceptible to overfishing; if so, why and how we can better manage these species. I present evidence that aggregate fish spawners are especially vulnerable because of both increased catchability (lethal effects) and biological factors (nonlethal effects). For these species to continue contributing to food security and livelihoods while retaining their ecosystem function, a truly precautionary approach is essential to reduce the risk of declines, particularly in the case of small-scale commercial fisheries of low-productivity species and where management and monitoring are lacking. There is a pressing need to mainstream spawning aggregations into marine resource management. [ABSTRACT FROM AUTHOR]

Independent of the effects of spawning-stock biomass (SSB), environmental variability in juvenile production, driven by factors such as temperature and food supply, have considerable potential to influence population resilience to fishing and depletion. Here, we analyse 18 time-series of Atlantic cod (Gadus morhua) stocks and empirically estimate this “environmental variability” in recruit-per-spawner (RPS) ratios. We then investigate the role of environmental recruitment variability on population resilience to fishing and ability to recover following depletion. To this end, cod population dynamics are simulated through a period of fishing, followed by a period of recovery, with alternative scenarios of recruitment variability and autocorrelation within it. The major effect of environmental recruitment variability is manifested through uncertainty. Firstly, the higher the recruitment variability, the shorter and less variable the time required for the population to decline below 15% of its carrying capacity, K. Secondly, higher variability leads to higher uncertainty in recovery time. Both these patterns are further strengthened by autocorrelation. Our findings suggest that increased environmental recruitment variability decreases resilience to fishing and increases uncertainty in recovery, thus challenging some traditional views that variability confers high productivity and rapid ability to recover from collapse. [ABSTRACT FROM PUBLISHER]

Wakefield, C. B., Newman, S. J., Marriott, R. J., Boddington, D. K., and Fairclough, D. V. 2013. Contrasting life history characteristics of the eightbar grouper, Hyporthodus octofasciatus (Pisces: Epinephelidae), over a large latitudinal range reveals spawning omission at higher latitudes. – ICES Journal of Marine Science, 70: 485–497.Demographic data on deep-water groupers are limited despite them being highly exploited throughout the Indo-Pacific. In Western Australia, the continuous distribution of the eightbar grouper, Hyporthodus octofasciatus, spans tropical to temperate waters over ∼3500 km from 12°S–35°S. The maximum age was markedly higher in the northern tropical waters than in southern temperate waters, i.e. 47 vs 20 years. Females attained a significantly larger length-at-age in southern temperate waters. Macroscopic and microscopic examination of gonads and annual trends in mean monthly gonadosomatic indices (GSIs) were used to determine that this monandric protogynous hermaphrodite spawns from late spring to summer (October–February) in northwestern Australia. In the temperate waters of WA, there was no evidence of reproduction and no males were observed south of ∼30°S latitude. The lengths at which 50% of female H. octofasciatus matured and changed sex were estimated from northern tropical populations at 560 mm (6.1 years) and 1022 mm (≥11 years). Although the population connectivity of H. octofasciatus is unknown, the spawning omission in temperate waters suggests recruitment from the northern tropical areas and highlights the importance of preserving spawning stocks in those northern waters. [ABSTRACT FROM PUBLISHER]

Wells, R. J. D., James H. Cowan Jr, and William F. Patterson III. 2008. Habitat use and the effect of shrimp trawling on fish and invertebrate communities over the northern Gulf of Mexico continental shelf. – ICES Journal of Marine Science, 65: 1610–1619. The goals of this study were to characterize habitat-specific fish and invertebrate community structure over sand, shell-rubble, and natural reef substrata, and to assess the effects of trawling on the sand and shell-rubble habitats and their associated communities during quarterly trawl surveys over a 2-year period. Fish and invertebrate communities differed significantly among habitat types [analysis of similarities (ANOSIM); Global R = 0.436, p < 0.001), and with respect to trawling exposure (ANOSIM; Global R = 0.128, p < 0.001). Habitat characteristics were quantified from video transects sampled with a remotely operated vehicle, and included percentage coverage of tubeworms, bryozoans, anemones, corals, and algae, significantly affecting fish community structure. Diversity indices differed among habitats, with the highest Shannon diversity (H′) and Pielou's evenness (J′) over shell-rubble, specifically non-trawled shell-rubble. In addition, higher values of H′ and J′ were found over trawled sand relative to non-trawled sand habitats. Length frequency distributions of several abundant fish species showed truncated size distributions over trawled and non-trawled habitats and were both habitat- and species-specific. The study describes habitat-specific differences in community structure, highlighting the differences between trawled and non-trawled areas on the northern Gulf of Mexico continental shelf. [ABSTRACT FROM PUBLISHER]