The relative value of different estuarine nursery areas in North Carolina for transient juvenile marine fishes

Offshore winter-spawned fishes dominate the nekton of south-eastern United States estuaries. Their juveniles reside for several months in shallow, soft bottom estuarine creeks and bays called primary nursery areas. Despite similarity in many nursery characteristics, there is, between and within species, variability in the occupation of these habitats. Whether all occupied habitats are equally valuable to individuals of the same species or whether most recruiting juveniles end up in the best habitats is not known. If nursery quality varies, then factors controlling variation in pre-settlement fish distribution are important to year-class success. If nursery areas have similar values, interannual variation in distribution across nursery creeks should have less effect on population sizes or production. I used early nursery period age-specific growth and mortality rates of spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus)—two dominant estuarine fishes—to assess relative habitat quality across a wide variety of nursery conditions, assuming that fish growth and mortality rates were direct reflections of overall physical and biological conditions in the nurseries. I tested the hypothesis that habitat quality varies for these fishes by comparing growth and mortality rates and distribution patterns across a wide range of typical nursery habitats at extreme ends of two systems. Juvenile spot and Atlantic croaker were collected from 10 creeks in the Cape Fear River estuary and from 18 creeks in the Pamlico Sound system, North Carolina, during the 1987 recruitment season (mid-March–mid-June). Sampled creeks were similar in size, depth, and substrates but varied in salinities, tidal regimes, and distances from inlets. Spot was widely distributed among all the estuarine creeks, but was least abundant in the creeks in middle reaches of both systems. Atlantic croaker occurred in the greatest abundance in oligohaline creeks of both systems. Instantaneous growth rates derived from daily otolith ages were generally similar for all creeks and for both species, except that spot exhibited a short-term growth depression in the upriver Pamlico system creeks—perhaps the result of the long migration distance of this species to this area. Spot and Atlantic croaker from upriver oligohaline creeks exhibited lower mortality rates than fish from downstream polyhaline creeks. These results indicated that even though growth was similar at the ends of the estuaries, the upstream habitats provided conditions that may optimize fitness through improved survival.

Current velocity and catch efficiency in sampling settlement-stage larvae of coral-reef fishes

Light traps and channel nets are fixed-position devices that involve active and passive sampling, respectively, in the collection of settlement-stage larvae of coral-reef fishes. We compared the abundance, taxonomic composition, and size of such larvae caught by each device deployed simultaneously near two sites that differed substantially in current velocity. Light traps were more selective taxonomically, and the two sampling devices differed significantly in the abundance but not size of taxa caught. Most importantly, light traps and channel nets differed greatly in their catch efficiency between sites: light traps were ineffective in collecting larvae at the relatively high-current site, and channel nets were less efficient in collecting larvae at the low-current site. Use of only one of these sampling methods would clearly result in biased and inaccurate estimates of the spatial variation in larval abundance among locations that differ in current velocity. When selecting a larval sampling device, one must consider not only how well a particular taxon may be represented, but also the environmental conditions under which the device will be deployed.

Chronic and catastrophic influences of the environment on the population dynamics of the common fishes [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Seasonal, interannual, decadal and centennial influences on population dynamics have been described for several species. It now seems possible to interpret environmental changes that initiate population change ...

Population studies of three species of ribbon fishes off the Bombay coast

Populations of three species of ribbonfishes (Trichiurus lepturus, Lepturacanthus savala, Euplerogrammus muticus) off the Bombay coast were studied for meristic and morphometric characters. All meristic characters except pectoral fin ray count, showed interspecific as well as intraspecific variations. Regression studies for various characters showed a linear relationship and high degree of correlation to the total and head lengths. Variations between the sexes were found insignificant. A comparison of the mean ratios of body parts of samples from Bombay and Mandapam showed significant variations for L. savala and E. muticus.

Developmental characters of Psettina Iijimae (Jordan and Starks), bothid flat fishes - Pisces

Post larval stages of Psettina Iijimae ranging from 1.8 mm NL to 44.6 mm SL collected during Naga Expedition and International Indian Ocean Expedition (IIOE) are described. The characteristics which help to identify larval stages of Psettina are: the presence of pigmented urohyal appendage in early stages which is progressively reduced during flexion stages and which disappears in later postflexion stages, the meristics, the spines on urohyal and posterior basipterygial processes and the absence of spines on cleithra. The P. iijimae can be distinguished by the presence of spines on the median fin rays which differentiate near the baseosts along the dorsal and ventral body wall much before the fin rays. The larvae of P.iijimae were more abundant in the Gulf of Thailand compared to South China Sea and Indian Ocean.

Use of homeo drug for curing ulcerative syndrome in fishes

Fungal infection was observed in Catla catla and Labeo rohita cultured in two private fish farms. The later stage of the infection resulted in ulcerations followed by haemorrhage on the dorsal surface of the body. Initially, usual treatments of copper sulphate, potassium permanganate and common salt solution were tried, but no improvement was observed. Then repeated intramuscular injections of homeopathic drug Heaper Sulpher and Arnica spray were given with encouraging results. Infection reported in another farm was also successfully controlled using a similar treatment.

Seasonal variation and species diversity of fishes in the Neyyar River of the Western Ghats

Temporal variation in the abundance of fish populations and diversity of assemblages in different sections of the Neyyar River in the Western Ghats were investigated during the year 1984. A decreasing trend in the abundance of fishes from the headwaters downwards has been noted. The fish community is represented by 33 species assignable to 15 families. The diversity indices of Shannon-Wiener and Margalef and Pielou's evenness have been calculated. The diversity indices are discussed in the light of species richness in different sectors.

On the identification of the early developmental stages of clupeiform fishes from Indian waters

Among about 65 species of clupeiform fishes present in the seas around India, most are distributed along both the east and west coasts and have similar spawning seasons and spawning grounds. The most difficult problem experienced with regard to the identification of their early developmental stages is the overlapping sets of diagnostic features among many species within the same genus as well as among species belonging to two or more genera. From studies carried out recently, the present paper sites a few instances wherein certain subtle characters have been used for distinguishing the early developmental stages of a few allied species.

Ascorbic acid turnover in the ocular tissues of some fishes

The ascorbic acid turnover from the ocular tissues of 11 species of fishes from a culture pond and the river Godavari (Andhra Pradesh, India) has been studied. The free ascorbic acid and ascorbigen contents were more in the case of bottom or deep dwelling fishes and the least in the case of surface living forms, depending upon the light penetration in the area that each species inhabits. The enzymic utilization and ascorbic acid-macromolecule complex varied among the fishes possibly depending upon individual energy requirements and not upon light intensity. No size-related or sex-related variation was observed. No variation was observed between riverine and pond-reared fishes of the same species.

Studies on the biochemical composition of some freshwater fishes. Pt. 1. Muscle

Twenty five different species belonging to 16 genera of freshwater fishes were analysed for protein, fat, moisture, ash, carbohydrate, phosphorus, calcium and total iron content in their muscle. Calorific value for protein, fat and carbohydrate fractions and total calories for each species were also calculated.

Studies on the biochemical composition of some freshwater fishes. Pt. 2. Liver

Although considerable work has been done on the composition of fish liver oils, most of which includes the study of various vitamins and fatty acids, little attention has been paid towards the composition of fish liver as a whole.

Studies on the biochemical composition of some freshwater fishes. Pt. 3. Ovary

Biochemical composition of the spent ovaries of 23 different species of freshwater fishes showed a much lower value for protein and fat with higher moisture content than those of the ripe eggs, suggesting an inverse relationship between fat and moisture. Ovaries during the recovering phase showed fairly high values of phosphorus, but lower than those for the ripe eggs. Higher values of calcium and iron in spent ovaries than those in ripe eggs probably suggest that there is a greater requirement of calcium and iron during the spent phase of the gonads.

Studies on the biochemical composition of some freshwater fishes. Pt. 1. Muscle

Twenty five different species belonging to l6 genera of freshwater fishes were analyzed for protein, fat, moisture, ash, carbohydrate, phosphorus, calcium and total iron content in their muscle. Calorific value for protein, fat and carbohydrate actions and total calories for each species were also calculated.

Sulphur and methionine content of some fresh water fishes of Madras

The importance of sulphur amino acids, especially of methionine, in our nutrition is too well known to be emphasized. But adequate data on the sulphur and methionine contents of the cheapest of our animal foods viz., fish, are not available. In this note, the total sulphur and methionine content of 18 common fresh water fishes is presented. Total sulphur was determined by Osborne perioxide method (Winton & Winton, 1945) and methionine by the colorimetric method of Horn. (Horn et al., 1946)