The teleost family Sciaenidae, collectively known as the croakers and drums because of their propensity for making sound, includes roughly 70 genera and 270 species worldwide. Although many other groups of fish also communicate using sound, the sciaenids are unique in the diversity of their sound production mechanisms, variety of sounds produced, and structural variation in sound-detecting structures. This paper reviews the bioacoustics of sciaenid fishes, including mechanisms involved in the production and reception of sound, the types of sounds produced, and the functions of these sounds. We propose the hypothesis that the unusual diversity in the design of the structures associated with sound production and detection is correlated with a similar diversity in how these structures function. Production and detection of sound appear to be important aspects of sciaenid behavior. But despite the vast literature on sciaenid sound production, we know relatively little about the biological significance of their sounds. This lack of understanding leaves plenty of room for research by physiologists, bioacousticians, behavioral ecologists, and fisheries scientists.[Article] FIGURE 1.-Swim bladders of selected sciaenids. The shaded areas represent sonic muscles and the dashed horizontal lines the point at which the septum transversum merges with the body wall ventrally. The dashed vertical lines (partial or complete) divide the diagrams into left and right portions, each of which pertains to a separate species. Types IÀVI are explained in Table 2; scientific names not given below are in Table 1. The figure is reproduced from Chao (1986). First row.-A (type I): left side ¼ spot, right side ¼ spotted drum Equetus punctatus; B (type I): left side ¼ shorthead drum Larimus breviceps, right side ¼ banded drum L. fasciatus; C (type II): left side ¼ king weakfish Macrodon ancylodon, right side ¼ scalyfin corvina; D (type III): left side ¼ Peruvian banded croaker Paralonchurus peruanus, right side ¼ totoaba; E (type III): left side ¼ smalleye croaker Nebris microps, right side ¼ Atlantic croaker; F (type V): left side ¼ red drum, right side ¼ corvina Sciaena gilberti; G (type IV): left side ¼ spotfin croaker Roncador stearnsii, right side ¼ white croaker; H (type IV): black drum. Second row.-A (type IV): meagre Argyrosomus regius; B (type III): boe drum Pteroscion peli; C (type III): Angola croaker Miracorvina angolensis; D (type III): blackmouth croaker Pentheroscion mbizi; E (type III): longneck croaker (also known as flathead captainfish) Pseudotolithus typus; F (type III): cassava croaker (also known as captainfish) P. senegalensis. Third row.-A (type III): kathala croaker Kathala axillaries; B (type III): Chinese bahaba Bahaba taipingensis; C (type III): left side ¼ pama croaker Otolithoides pama, right side ¼ Plagioscion sp. from the Amazon River; D (type III): left side ¼ panna croaker Panna microdon, right side ¼ Boeseman croaker Boesemania microlepis; E (type IV): pawak croaker Pennahia pawak; F (type IV): left side ¼ pric...

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We recorded 31 species in the stomachs of 146 coastal bottlenose dolphins (Tursiops truncatus) from North Carolina, U. S. A. Sciaenid fishes were the most common prey (frequency of occurrence = 95%). By mass, Atlantic croaker (Micropogonias undulatus) dominated the diet of dolphins that stranded inside estuaries, whereas weakfish (Cynosicon regalis) was most important for dolphins in the ocean. Inshore squid (Loligo sp.) was eaten commonly by dolphins in the ocean, but not by those in the estuaries. There was no significant pattern in prey size associated with dolphin demography, but the proportion of the diet represented by croaker was higher for males than for females, and mature dolphins ate more croaker than did juveniles. Dietary differences between dolphins that stranded in the estuaries and those that stranded on ocean beaches support the hypothesis that some members of the population inhabit the ocean primarily while others reside principally in estuaries. The overwhelming majority of prey were soniferous species (75% of numerical abundance), which is consistent with the hypothesis that bottlenose dolphins use passive listening to locate noise‐making fishes. However, spatiotemporal patterns in consumption of Sciaenid fishes did not coincide with their spawning, which is when peak sound production is thought to occur.

Brevetoxins and ciguatoxins are closely related potent marine neurotoxins. Although ciguatoxins accumulate in fish to levels that are dangerous for human consumption, live fish have not been considered as potential sources of brevetoxin exposure in humans. Here we show that, analogous to ciguatoxins, brevetoxins can accumulate in live fish by dietary transfer. We experimentally identify two pathways leading to brevetoxin-contaminated omnivorous and planktivorous fish. Fish fed with toxic shellfish and Karenia brevis cultures remained healthy and accumulated high brevetoxin levels in their tissues (up to 2675 ng g −1 in viscera and 1540 ng g −1 in muscle).Repeated collections of fish from St. Joseph Bay in the Florida panhandle reveal that accumulation of brevetoxins in healthy fish occurs in the wild. We observed that levels of brevetoxins in the muscle of fish at all trophic levels rise significantly, but not to dangerous levels, during a K. brevis bloom. Concentrations were highest in fish liver and stomach contents, and increased during and immediately following the bloom. The persistence of brevetoxins in the fish food web was followed for 1 year after the K. brevis bloom.

Blooms of the toxic alga Karenia brevis, commonly referred to as 'Florida red tides,' occur along Florida's west coast on a near-annual basis, causing massive fish kills. However, few quantitative data on the ecological effects of red tides on fish communities exist. We surveyed fish communities in 5 habitats within Sarasota Bay and the adjacent Gulf of Mexico during the summers of 2004 to 2007 using a purse seine. We collected contemporaneous data on fish densities, fish species composition, K. brevis cell densities, water temperature, salinity, dissolved oxygen, and turbidity. Fish density (catch per unit effort [CPUE]) and species richness were significantly lower in all habitats during red tides. Shannon-Wiener diversity indices were significantly lower in 4 of 5 habitats during red tides. Classification and regression tree analysis showed significant negative relationships between K. brevis density and non-clupeid CPUE, and between K. brevis density and species richness. Fish community structure differed significantly between red tide and non-red tide conditions. Canonical correspondence analysis showed that of all the environmental factors investigated, K. brevis density had the greatest influence on community structure. Most trophic guilds were negatively associated with K. brevis density, whereas the guild that included clupeids was positively associated with K. brevis density. Florida's fish kill database showed that 96% of local fish kills during 2003 to 2007 occurred during red tides. We concluded that red tides caused the observed changes in fish abundance and community structure. Harmful algal blooms occur throughout the world and may play an important, yet little understood, role in regulating fish communities.

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Ten prey taxa were recorded from the stomach contents of eight long‐finned pilot whales (Globicepbala melas) independently stranded along the U.S. mid‐Atlantic coast. Relative importance of prey species was determined by methods that incorporate prey frequencies of occurrence, proportions of numerical abundance, and proportions of reconstructed mass. Separate analyses of trace (free, durable body parts representing well‐digested prey items) and non‐trace (relatively intact prey specimens) food material were conducted in order to address biases caused by differential rates of digestion and passage through the gastrointestinal tract. Different measures of prey importance yielded varying results, but the long‐finned squid (Loligo pealei) was the most important prey species regardless of how prey importance was defined. Fishes were relatively unimportant in the diet. Our results indicate that the diets of western North Atlantic long‐finned pilot whales differ substantially from what has been previously reported in the literature and that results from food‐habits studies that utilize different techniques may not be comparable.