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Weight-length relations of fishes are useful for estimation of biomass from length observations, e.g., in fisheries or conservation research. Here we provide some guidance to authors of such papers, in order to facilitate the publication and review process

Removal of important predators by fishing can result in trophic cascades and indirect effects on marine benthic communities. Indirect effects are especially evident when prey populations released from predation by fishing have the ability to modify entire benthic communities, as do sea urchins. Sea urchins have been shown to dramatically alter the underwater landscape by grazing, by converting stands of large erect algae into coralline barrens. In the western Mediterranean, a recent extension of coralline barrens into areas formerly dominated by erect algal assemblages has been attributed to release of predation on sea urchins by overfishing. Most suggestions concerning the transition from erect algal assemblages to coralline barrens, however, have been speculative, and little descriptive and experimental work has been carried out to verify the hypothesis that fish predation on sea urchins (and its subsequent release by overfishing) drives this transition. Here we critically review the literature concerning the effect of fishing on sea urchin populations and its subsequent maintenance of different algal assemblages in the Mediterranean. The extant data cannot refute the \"fishes as important predators\" model, but we argue that other processes (recruitment, pollution, disease, large-scale oceanographic events, sea urchin harvesting, food subsidies, and availability of shelters) may also be important in regulating the structure of Mediterranean algal assemblages.

About 300 species belonging to four superfamilies (Gnathostomatoidea, Habronematoidea, Physalopteroidea and Thelazioidea) of the nematode suborder Spirurina are known as the adult parasites of freshwater, brackish-water and marine fishes. They are placed in four families, of which the Gnathostomatidae are parasites of elasmobranchs, whereas Ancyracanthus contains one species in teleosts; the Physalopteridae is represented in fish by four genera, each with several species in both elasmobranchs and teleosts. The majority of fish spirurines belongs to the Rhabdochonidae, which includes 10 genera of species parasitizing mainly teleosts, rarely elasmobranchs, and the Cystidicolidae with about 23 genera. Most species of these parasites are poorly known. In Cystidicolidae, several genera have been based on details in the cephalic structures visible only with the aid of SEM, but it will be evident whether or not these tiny features are of generic importance only when more cystidicolids are described using SEM and comparative molecular data become available. Data on the biology of fish spirurines are scarce. In known cases, their life cycles involve aquatic arthropods as intermediate hosts; sometimes, fish paratenic hosts are known to occur in cystidicolids parasitizing as adults piscivorous definitive hosts. Some spirurine species are pathogenic and are known as causative agents of serious fish diseases.

:  The distribution of mercury in the muscle and other tissues was determined in 23 species of fishes and invertebrates. This study reveals species‐specific patterns of mercury accumulation in the muscle of tuna and alfonsino. Consistently high levels of total mercury were found in Beryx splendens (0.78 ± 0.56 µg/g), Atlantic Thunnus thynnus (0.42 ± 0.06 µg/g), Pacific T. thynnus (0.59 ± 0.34 µg/g), Thunnus obesus (0.98 ± 0.34 µg/g), Makaira nigricans (0.56 ± 0.05 µg/g), Tetraptrus audax (0.51 ± 0.08 µg/g), and Xiphias gladius (0.47 ± 0.24 µg/g). Other fish species had lower levels of total mercury or methylmercury in muscle than the maximum permitted level of mercury in fish in Japan (0.4 µg/g). Total mercury and methylmercury levels in the muscles of T. thynnus, T. obesus, and B. splendens were closely correlated with body weight.

The food habits of 67 fish species collected from the mangrove estuary of the Urauchi River, Iriomote Island, southern Japan were investigated using gut content analysis. Ontogenetic changes in food preference were recognized in nine species, including mugilids, gerreids, mullids, gobiids and tetraodontids. In most cases, juveniles of these species fed mostly on small crustaceans (e.g. calanoid and cyclopoid copepods and gammaridean amphipods) or detritus. With their subsequent growth, larger prey items (e.g. crabs and polychaetes) became dominant. A cluster analysis based on dietary overlaps showed that the mangrove fish assemblage comprised eight trophic groups (zooplankton, small benthic crustacean, large benthic crustacean, polychaete, fish, detritus, plant and insect feeders). Of these, large and small benthic crustacean feeders, which consumed mainly crabs and gammaridean amphipods, respectively, were the most abundantly represented in terms of species, whereas polychaete and insect feeders were each represented by only two species.

The nematode superfamily Dracunculoidea includes 166 recognized species, of which 150 are parasitic in about 300 species of freshwater, brackish-water and marine fishes. Fish dracunculoids are placed in 31 genera belonging to eight of the nine dracunculoid families: Anguillicolidae, Daniconematidae, Guyanemidae, Lucionematidae, Micropleuridae, Philometridae, Skrjabillanidae, and Tetanonematidae. Most species of these largely histozoic parasites are poorly known and males of the majority of species and of eight genera have not yet been discovered. The present classification system of dracunculoids as a whole does not reflect phylogenetic relationships. In known cases, their life cycles involve copepods, ostracods or branchiurids as intermediate hosts and, sometimes, fish paratenic hosts are known to occur in dracunculoid species parasitizing as adults piscivorous definitive hosts. Some species of dracunculoids, particularly of philometrids, are highly pathogenic and are known as agents of serious fish diseases. Further detailed studies on fish dracunculoids are necessary.

A review of recent literature showed that methyl mercury concentrations contributed less than 1 per cent of total mercury in precipitation in industrial areas. Following atmospheric deposition the mercury levels in fish were affected by environmental parameters within the catchment and the aquatic system demonstrating the importance of assessing the contributions of local geology to background mercury levels in fish (estimated as 0.2-1.0 mg per kg compared to the preindustrial level of 0.15 mg per kg). The methyl mercury:total mercury ratio in fish muscle tissue was generally unity regardless of environmental contamination and the major route of methyl mercury uptake in fish was biomagnification from sediment, food and respiration following inputs from precipitation, runoff and in-lake methylation. Aquatic systems with good acid-buffering properties had low fish mercury levels due to reduced production of methyl mercury and maintenance of gill function. Catchment and atmospheric processes combined with many physicochemical variables in the aquatic environment to influence the bioaccumulation rate and absolute concentration of mercury in fish but sufficient data were now available to develop an axiom for identifying aquatic systems likely to be susceptible to bioaccumulation from atmospherically-derived mercury. There are 250 references.

The suitability of various under-utilized fish species as starting material for the production of a miso-like fermented product was studied. To the end, four under-utilized fishes and shellfishes - spotted mackerel, lizard fish, horse mackerel, and common squid - were fermented, under either washed or unwashed conditions, with malt-rice (kome-koji) as a starter, and their quality parameters assessed. The protein content of the fermented fish pastes (18.1-22.4%) was superior to that of fermented soy paste (12.9%). Our analyses of other physico-chemical parameters of the finished products, including free amino acid, oligopeptide, organic acid, and mineral content, also revealed the potential utility of both washed and unwashed fish meat for the production of miso-like fermented fish pastes. Sensory evaluation revealed the potential of the washing step to produce a consistent product for large-scale production.

In this study, 30 strains of the genus Bacillus were isolated from various fresh fishes obtained from fish markets in Ankara, Turkey. They were identified as Bacillus pasteurii, Bacillus badius, Bacillus circulans, Bacillus licheniformis, Bacillus megaterium, Bacillus thuringiensis, Bacillus brevis, Bacillus cereus, Bacillus sphaericus, Bacillus subtilis, Bacillus coagulans, Bacillus lentus, and Bacillus pumilus. When poly-beta-hydroxybutyrate (PHB) production by these strains was determined by spectrophotometry, it was found that PHB production ranged from 0.81-23.38% (w/v). PHB production and productivity were highest for B. pasteurii P2 (20.58% w/v) and B. lentus P18 (23.38% w/v). Furthermore, B. pasteurii P2 and B. lentus P18 were examined for PHB production using different carbon and nitrogen sources and in combined medium containing both carbon and nitrogen sources. The amounts of PHB produced by the strains in these media were more different than the amounts of PHB produced in nutrient broth medium.

How much do animals eat? Why do eating patterns change? How do physiological, dietary, and environmental factors affect feed intake? This volume, a comprehensive overview of the latest animal feed intake research, answers these questions with detailed information about the feeding patterns of fishes, pigs, poultry, dairy cows, beef cattle, and sheep. Equations for calculating predicted feed intake are presented for each animal and are accompanied by charts, graphs, and tables.