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A predator's ability to capture prey depends critically on how it coordinates its approach in response to a prey's motion. Flying insects, bats and raptors are capable of capturing prey with a strategy known as parallel navigation, which allows a predator to move directly towards the anticipated point of interception. It is unclear if predators using other modes of locomotion are employing this strategy when pursuing evasive prey. Using kinematic measurements and mathematical modelling, we tested whether bluefish (Pomatomus saltatrix) pursue prey fish (Fundulus heteroclitus) with parallel navigation. We found that the directional changes of bluefish were not consistent with this strategy, but rather were predicted by a strategy known as deviated pursuit. Although deviated pursuit requires few sensory cues and relatively modest motor coordination, a comparison of mathematical models suggested negligible differences in path length from parallel navigation, largely owing to the acceleration exhibited by bluefish near the end of a pursuit. Therefore, the strategy of bluefish is unlike flying predators, but offers comparable performance with potentially more robust control that may be well suited to the visual system and habitat of fishes. These findings offer a foundation for understanding the sensing and locomotor control of predatory fishes. [ABSTRACT FROM AUTHOR]

Little is known about the behavioral responses of fishes at low temperatures. Of particular interest are predator–prey interactions because feeding at low temperature is necessary for the overwinter survival of many species. This experiment examined how low temperatures affect behavioral interactions between bluefish ( Pomatomus saltatrix L.) and two sizes of bay anchovy ( Anchoa mitchilli V.) prey. Temperature had an effect on multiple responses of predator–prey encounters including the approach distance of bluefish towards prey, attack and escape speeds, and prey handling time. The reaction distance of prey was important in determining the outcome of an attack; anchovy reacting at a greater distance from an attacking bluefish escaped more often. However, temperature did not have an effect on either reaction distance or bluefish capture success. The influence of prey size depended on how capture success was defined. Bluefish ability at catching prey was not affected by anchovy size, but larger prey were ingested less frequently due to a greater incidence of prey being dropped in trials with large anchovy. Further, bluefish had greater difficulty handling and ingesting prey at lower temperatures, especially for larger prey. At the lowest temperature treatment small anchovy were readily consumed, but no attacks were made on larger prey. This shows that bluefish modify prey size-selectivity behavior based on temperature, which probably results from a perceived inability to handle and ingest large prey at low temperatures. These results suggest that at low winter temperatures bluefish are restricted to smaller prey. [ABSTRACT FROM AUTHOR]

Bluefish ( Pomatomus saltatrix) has a worldwide distribution, being targeted by fishers all along its range, which includes the Brazilian coast. We formulated and checked hypotheses regarding bluefish diet, migration, and reproduction based on fishers’ local ecological knowledge (LEK). We interviewed 49 experienced fishers (40 years and older) from five communities along the Brazilian coast and analyzed the diet and reproduction of 185 fish. According to fishers’ LEK, the bluefish spawn mainly during the winter, migrate throughout year (from the South to North), and eat mainly small fish (Clupeidae and Engraulidae), plus shrimp and squid. The biological survey confirmed the hypothesis on bluefish diet (78% of fish with stomach contents had fish in their stomachs) but not that on reproduction: we observed larger fish and more fish with visible eggs during summer and autumn. Migratory movements mentioned by fishers agreed with literature data. Besides providing data to support conventional management decisions in the absence of biological surveys, our results and approach could help involve fishers in management, thus contributing to development of co-management systems more suitable to local conditions and to complex tropical fisheries. [ABSTRACT FROM AUTHOR]

Abstract: We examine the age and growth of bluefish, Pomatomus saltatrix, along the U.S. east coast collected from Florida to New York during 2001–2003 (n =2652). We describe a new preparation technique for the otoliths that increases readability, and provide criteria for the interpretation of otolith microstructure. Annulus formation in otoliths for bluefish is validated for fish aged 1–8 using marginal increment analysis. This extends validation by 4 years to include the preponderance of age classes in the catch. A side-by-side comparison of ageing precision and bias was performed between otoliths and scales. When compared, precision was highest with sectioned otoliths, exceeding 87% across all years, and exceeding 99% within 1 year, up to age 13. In contrast, scales tended to over-age ages 1 through 5, and under-aged age 7 and older compared to sectioned otoliths. We used these otolith-based ages to evaluate age distribution in gears used in the fishery and to evaluate size-at-age data and to estimate growth parameters from the catch. No significant differences in the von Bertalanffy growth parameters were found in comparison by sex, year and between the South Atlantic and Middle Atlantic Bights using Kimura''s likelihood-ratio test. The estimated von Bertalanffy model growth parameters for bluefish along the coast were L inf =815.3mm ±15.3, k =0.311±0.03, t 0 =−0.301±0.18. These findings are then used to examine the implications for management of this ecologically and economically important coastal pelagic species. [Copyright &y& Elsevier]

Abstract: The reproductive biology of bluefish (Pomatomus saltatrix) along the U.S. East Coast is examined from a collection 1437 females sampled from nearshore to the continental slope and from Florida to New York over a period of 3 years (2001–2003). In most years concurrent sampling along the coast was conducted over spring and summer months to resolve the initiation of spawning. We examined the spawning location, pattern and timing, and calculated the fecundity of fish from 600 to 840mm in length. Based on macro- and microscopic analysis of female gonads, bluefish are multiple spawners with indeterminate fecundity. The presence of all stages of development in fully mature ovaries further indicates that bluefish have asynchronous oocyte development. Mean age at first maturity for female bluefish was ∼1.90 years and 480mm total length. Mean batch fecundity was 402,247 eggs and ranged from 114,513 to 920,746 eggs, depending on age and weight. Direct observation of gonads showed imminent spawning in Florida and North Carolina during March to April, and from April to August from Virginia to New York. Given the progression of oocyte development over the range of space and time we sampled, we suggest that bluefish exhibit continuous spawning during their migration from the South Atlantic Bight (SAB) to Middle Atlantic Bight (MAB). [Copyright &y& Elsevier]

Abstract: The genetic and morphological variation of Pomatomus saltatrix were studied based on morphometric and meristic analyses of samples collected throughout the Black Seas, Marmara, Aegean and eastern Mediterranean Seas. In discriminant function analysis, plotting first and second discriminant functions explained 61 and 77% of the between-group variation for morphometric and meristic analyses, respectively, and indicated existence of three morphologically differentiated groups of P. saltatrix. Consistent differences in the summer and winter samples of the eastern Black Sea, the adjacent sea populations of western Black Sea, Marmara Sea and Aegean Sea, which were overlapping and northeastern Mediterranean samples were observed. The detected pattern of morphological differentiation also reflects their geographic isolation. The overall random assignment of individuals into their original population was moderate for morphometric (54%) and meristic (64%) characters. Both for morphometric and meristic analysis, the highest reclassification rate was observed for the eastern Black Sea and northeastern Mediterranean Sea samples, the most clearly isolated groups. Examination of the contribution of each morphometric and meristic character to the first and second discriminant functions revealed that the observed differences were mainly from head measurements, body depth, lateral scale and vertebrate numbers, indicating these characters to be important in the description of population characteristics. Mantel''s test showed that the Mahalanobis distance between the populations both for morphometric (r =−0.282; P =0.226) and meristic (r =0.632; P =0.119) were not significantly associated with their geographical distances. [Copyright &y& Elsevier]

Examination of 203 adult bluefish (Pomatomus saltatrix) from Long Island, New York, in 2002 and 2003 and 66 from the Outer Banks, North Carolina, in 2003 revealed the presence of dracunculoid nematodes (Philometra saltatrix) in the ovaries of female fish. Percent prevalence reached 88% in July and then decreased after the peak of the spawning season. Bluefish contained up to 100 parasites per fish. Infection was associated with a range of disorders, including hemorrhage, inflammation, edema, prenecrotic and necrotic changes, and follicular atresia, that may prevent proper development of oocytes and probably affect bluefish fecundity. Historical occurrences, life cycle, and geographical distribution of this nematode remain largely unknown, but may play important roles in recruitment processes of bluefish. [ABSTRACT FROM AUTHOR]

This paper examines a scientific decision making process that was used as the basis of management decisions for Atlantic bluefish (Pomatomus saltator) in the United States. It is derived from a sociological case study of the use of scientific claims by both scientists and non-scientists in a debate over the management of this species along the US East Coast between 1996 and 1998. This paper focuses on how legal mandates, and responses to these mandates by management agencies, shaped the debate among fisheries scientists about the condition of the bluefish stock. It suggests that these mandates had a distorting effect that kept the scientists from making use of what they felt was their best scientific judgement. The paper also examines the difficulties encountered by the scientists in assigning an appropriate role to the precautionary principle. [Copyright &y& Elsevier]

The presence and foraging activities of predatory bluefish (Pomatomus saltatrix) differentially affect the foraging success of Roseate (Sterna dougallii) and Common Terns (S. hirundo), and depress the foraging activities of Roseate Terns. In the absence of bluefish, Roseate Terns had higher mean fishing success frequencies than Common Terns. This advantage was lost in the presence of bluefish, and Roseate Terns foraging success was inversely correlated with bluefish feeding intensity. Roseate Terns left foraging flocks more frequently as predatory fish activity increased and flock density increased. Conversely, the rate at which Common Terns left flocks was inversely correlated with predatory fish feeding and was unrelated to flock density. Bluefish may be considered keystone competitors in this system. [ABSTRACT FROM AUTHOR]