The atyid prawns of Dominica

The family of primitive prawns, Atyidae, are freshwater animals with a circumtropical distribution, but additionally some have penetrated into temperate regions. An intriguing aspect of their distribution is that, although they are, and have long been, freshwater crustaceans, they have succeeded in colonizing many oceanic islands. The West Indies is an area of interest, as representatives of several genera sometimes occur on one island. For its size, Dominica is particularly rich in this respect. The fauna of the island includes the most primitive living atyid (a West Indian endemic, Xiphocaris elongata) and 2 representatives of the most advanced genus, Atya. Each of the other 3 spp belongs to a separate genus. The feeding behaviour of the Dominican atyids is discussed in this article.

Water chemistry and osmoregulation in some arthropods, especially Malacostraca

This article briefly summarises some chief characteristics of osmoregulatory systems in malacostracan crustaceans, evolved to combat hydration, and the limitations thereby imposed on the salinity tolerance and distribution of these animals.

Polyphemus pediculus (L.) (Cladocera) as a possible indicator of water quality

Usually stenobiotic species are used as hydrobiological indicators of the degree of pollution in natural waters. Cladocera are eurybiotic organisms, therefore their role as specific indicators of the water quality is considered to be insignificant. However, considering new methods Cladocera at present are more and more often used as indicators of oligo- and mesosaprobic waters as well as of the presence of considerable amounts of easily degradable organic matter. Work over many years on the biology of Polyphemus pediculus, this striking representative of the order Cladocera, convinced the author of the possibility of using this species not only as an indicator of water purity but also for the estimation of the degree of water pollution as well as of water characteristics such as colour, turbidity, oxgen content and chemical composition. P. pediculus is one of the most common and abundant species of planktonic crustaceans in shallow waters of reservoirs, rivers, lakes, ponds and temporary water bodies.

The food of coarse fish

Remarkably little has been published on the feeding habits of the non-salmonid fishes of British fresh waters. The following report briefly summarizes the results obtained from the examination of the stomach contents of some 2,700 fish, belonging to 19 species, which were obtained during 1939. The results of all examinations of gut contents were analysed, species by species, upon a simple basis of the presence of different types of food. Foodstuffs were divided up into six main categories— fish, molluscs, insects, crustaceans, higher plants together with filamentous algae, and diatoms—and the occurrence of members of any of these categories was recorded for each fish.

The role of probiotics in aquaculture in Nigeria - a review

Aquaculture is beset by many problems especially diseases caused by bacteria as the major deteriorating factors. The use of vaccines and antimicrobial agents have been centered on disease control, but are associated with problems The development of antibiotic resistance among the microorganisms have become a global concern as a result of indiscriminate use of antibiotics. Several alternative suggestions for disease prevention have been on probiotics for its efficacy, low cost, less side effects and accessible to farmers. Probiotics is gaining a high priority in the developed countries with the aim of replacing conventional drugs. The principal bacterial groups tested as probiotic bacteria in culture of shrimps, crabs, oysters, fish and humans are Vibrio, Pseudomonas, Bacillus, Bifidobacteria and several Lactobacilli. Experiments have mainly been conducted with fish larvae, adult fish, crustaceans and animals where significant reduction in mortalities has been obtained. The purpose of this review is to create awareness of the role of probiotics in disease control in aquaculture as alternative to antibiotics.

Crustacés et Helminthes parasites de l'Albacore (Thunnus albacares) du Golfe de Guinée - note préliminaire

This note presents the results of a current study on the parasitism of the yellowfin Thunnus albacares in the Gulf of Guinea: a list of encountered crustaceans and helminths, remarks concerned with localisations, frequencies and intensities of the infestations is given. A hypothesis on the existence of three ecological stocks corresponding to three great fishing areas of the Gulf is suggested.

Le régime alimentaire de Dentex angolensis, Poll et Maul, 1953 (Sparidae)

The food of Dentex angolensis, studied from 386 stomachs, consists essentially of small epibenthic crustaceans and, with less importance, of fishes. A systematic list with abundance and occurrence is given here. It is noted that the composition of the stomach content can differ with depth and season.

Arctic charr from Ennerdale Water: a pilot study

There are three fish species in the north west of England, Arctic charr (Salvelinus alpinus, L.), schelly (Coreqonus lavaretus. L.), and vendace (C. albula, L.), which have been reported as rare and vulnerable and have been identified as requiring the preparation and implementation of a conservation management plan. The presence of Arctic charr in Ennerdale Water has resulted in it being designated as a Site of Special Scientific Interest. These fish and one race of the species in Lake Windermere are the only English populations of charr known to spawn in running water. Associated with Ennerdale charr is the copepod parasite Salmincola edwardsii which has not been recorded from any other charr inhabited waters of the Lake District. However, it has been recorded on charr from four Scottish Lochs (Stack, Lee, Tay and Doon). The unique nature of Ennerdale is further highlighted by the presence of two crustaceans, Mysis relicta and Limnocalanus macrurus. The former has been recorded in Ireland while the latter is not known to exist anywhere else in the British Isles. The aim of this pilot study was to obtain baseline data on charr that spawn in Smithy Beck and the River Liza. This would indicate the current status of the population and help identify areas requiring further investigation. A total of 161 fish (95 males and 66 females) was caught and tagged over the 3 day period, 141 from Smithy Beck and 20 from the Liza. The raw data of the findings is presented in two appendices.

Comparative feeding ecology of two elasmobranch species, Squalus blainville and Scyliorhinus canicula, off the coast of Portugal

The small-spotted catshark (Scyliorhinus canicula) (Linnaeus, 1758) and the longnose spurdog (Squalus blainville) (Risso, 1826) are two species occurring in the European and western African continental shelves with a wide geographical distribution. In this study, the diet of S. blainville and S. canicula off the Portuguese western Atlantic coast was investigated in 2006 by collecting monthly samples of these two species from local fishing vessels. In the stomachs of both species, crustaceans and teleosts were the dominant prey items, and molluscs, polychaetes, echinoderms, and sipunculids were found in lower abundance. In S. canicula, urochordate and chondrichthyan species were also observed in stomachs and were classified as accidental prey items. Scyliorhinus canicula consumed a broader group of prey items than did S. blainville. A significant diet overlap was observed, despite both species occupying different depth ranges over the continental shelf. Scyliorhinus canicula exhibited a consistency in diet composition among seasons, sexes, and maturity stages. Nonetheless, for both adults and juveniles, an increase in relative abundance of teleosts in the diet was observed in the spring and summer. This study provides evidence of the importance of S. canicula and S. blainville as benthic and pelagic predators along the western Atlantic coast.

Transitions in the morphological features, habitat use, and diet of young-of-the-year goosefish (Lophius americanus)

This study was designed to improve our understanding of transitions in the early life history and the distribution, habitat use, and diets for young-of-the-year (YOY) goosefish (Lophius americanus) and, as a result, their role in northeastern U.S. continental shelf ecosystems. Pelagic juveniles (>12 to ca. 50 mm total length [TL]) were distributed over most portions of the continental shelf in the Middle Atlantic Bight, Georges Bank, and into the Gulf of Maine. Most individuals settled by 50−85 mm TL and reached approximately 60−120 mm TL by one year of age. Pelagic YOY fed on chaetognaths, hyperiid amphipods, calanoid copepods, and ostracods, and benthic YOY had a varied diet of fishes and benthic crustaceans. Goosefish are widely scattered on the continental shelf in the Middle Atlantic Bight during their early life history and once settled, are habitat generalists, and thus play a role in many continental shelf habit

Development of larval and early juvenile penpoint gunnel (Apodichthys flavidus) (family: Pholidae)

The penpoint gunnel (Apodichthys flavidus) is a member of the perciform family Pholidae. Pholids, commonly referred to as gunnels, are eel-like fishes that inhabit the rocky intertidal and subtidal regions of the northern oceans and are often associated with macroalgae, such as Fucus spp. or kelp (Watson, 1996). Gunnels are ecologically important forage fishes that form part of the diet of birds and commercially important groundfish species (Hobson and Sealy, 1985; NMFS1; Golet et al., 2000). The diet of A. flavidus and other pholids comprises primarily harpactacoid copepods, gammarid amphipods, isopods, and other crustaceans (Cross, 1981). Apodichthys flavidus ranges along the west coast of North America from southern California to the Gulf of Alaska (Mecklenburg et al., 2002). Adult A. flavidus are distinguished from other pholids by their total vertebral counts, the presence of a thick and grooved first anal spine, a preanal length that is approximately 60% standard length (SL), and a dark green to light olive coloration (Yatsu, 1981). It is one of the largest pholids (up to 46 cm) and is important in the live fish trade for both home and public aquaria (Froese and Pauly2).

Diet composition of fish species from the southern continental shelf of Colombia

The diet composition of 30 fish species belonging to 16 families from the Pacific Coast of Colombia is described. Benthic crustaceans (37.5%) and bony fishes (23.7%, chiefly demersal) were the most important food items for the fish species analyzed. Data on diet composition of the fish species are presented for the first time which can be a source of information for trophic modeling.

Diet composition and daily ration estimates of selected trawl-caught fishes in San Miguel Bay, Philippines

The diet composition of fish caught in San Miguel Bay, Philippines, in April and May 1993 was studied. The diets of tiger-tooth croaker (Otolithes ruber), commerson's anchovy (Stolephorus commersonii); and the Indian anchovy (Stolephorus indicus) consisted mainly of zooplankton, primarily crustaceans. The stomach content of orangefin ponyfish (Leiognathus bindus) was found to consist mostly of detritus and unidentified materials. Daily rations estimated were: 1.90 g day super(1) for O. ruber of 17.3 g mean body weight (BW), 0.078 g day super(1) for S. commersonii) of 3.8 g mean BW, 0.062 g day super(1) for S. indicus of 3.9 g mean BW and 0.56 g day super(1) for L. bindus of 7.7 g mean BW.

Skimmer Trawl Fishery Catch Evaluations in Coastal Louisiana, 2004 and 2005

Fishery observers collected data from 307 tows during 96 trips aboard skimmer trawl vessels in Louisiana’s coastal waters from September 2004 through June 2005 to estimate catch rates of target and nontarget species, including sea turtles (Cheloniidae and Dermochelyidae), by area and season during commercial shrimping operations. About 16,965.7 kg of total catch were recorded during 517.0 hours of fishing operations. Based on weight extrapolations from species composition samples, penaeid shrimp (Penaeidae) dominated the catch at 66%, followed by finfish at 19%, nonpenaeid shrimp crustaceans at 7%, discarded penaeid shrimp at 6%, and debris at 3%. Noncrustacean invertebrates comprised less than 1%. Catch rates in kilograms per hour by category was 21.6 for penaeid shrimp, 6.2 for finfish, 2.2 for nonpenaeid crustaceans, 1.8 for discarded penaeid shrimp, and 0.9 for debris. White shrimp, Litopenaeus setiferus, other penaeid shrimp, and Gulf menhaden, Brevoortia patronus, were the top three dominant species by weight. Seasonally, a higher catch rate was observed from May through August 2005 for penaeid shrimp as compared with the September through December 2004 period. Conversely, the September through December 2004 period experienced a higher catch rate for finfish than during May through August 2005. No sea turtle interactions were documented.

The Fisheries for Mangrove Cockles,Anadaraspp., from Mexico to Peru, With Descriptions of Their Habitats and Biology, the Fishermen’s Lives, and the Effects of Shrimp Farming

This paper provides the first description of the mangrove cockle, Anadara spp., fisheries throughout their Latin American range along the Pacific coast from Mexico to Peru. Two species, A. tuberculosa and A. grandis, are found over the entire range, while A. similis occurs from El Salvador to Peru. Anadara tuberculosa is by far the most abundant, while A. grandis has declined in abundance during recent decades. Anadara tuberculosa and A. similis occur in level mud sediments in mangrove swamps, comprised mostly of Rhizophora mangle, which line the main-lands and islands of lagoons, whereas A. grandis inhabits intertidal mud flats along the edges of the same mangrove swamps. All harvested cockles are sexually mature. Gametogenesis of the three species occurs year round, and juvenile cockles grow rap-idly. Cockle densities at sizes at least 16–42 mm long ranged from 7 to 24/m2 in Mexico. Macrofaunal associates of cockles include crustaceans, gastropods, and finfishes. The mangrove swamps are in nearly pristine condition in every country except Honduras, Ecuador, and Peru, where shrimp farms constructed in the 1980’s and 1990’s have destroyed some mangrove zones. In addition, Hurricane Mitch destroyed some Honduran mangrove swamps in 1998. About 15,000 fishermen, including men, women, and children, harvest the cockles. Ecuador has the largest tabulated number of fishermen, 5,055, while Peru has the fewest, 75. Colombia has a large number, perhaps exceeding that in Ecuador, but a detailed census of them has never been made. The fishermen are poor and live a meager existence; they do not earn sufficient money to purchase adequate food to allow their full health and growth potential. They travel almost daily from their villages to the harvesting areas in wooden canoes and fiberglass boats at low tide when they can walk into the mangrove swamps to harvest cockles for about 4 h. Harvest rates, which vary among countries owing to differences in cockle abundances, range from about 50 cockles/fisherman/day in El Salvador and Honduras to 500–1,000/ fisherman/day in Mexico. The fishermen return to their villages and sell the cockles to dealers, who sell them mainly whole to market outlets within their countries, but there is some exporting to adjacent countries. An important food in most countries, the cockles are eaten in seviche, raw on the half-shell, and cooked with rice. The cockles are under heavy harvesting pressure, except in Mexico, but stocks are not yet being depleted because they are harvested at sizes which have already spawned. Also some spawning stocks lie within dense mangrove stands which the fishermen cannot reach. Consumers fortunately desire the largest cockles, spurning the smallest. Cockles are important to the people, and efforts to reduce the harvests to prevent overfishing would lead to severe economic suffering in the fishing communities. Pro-grams to conserve and improve cockle habitats may be the most judicious actions to take. Preserving the mangrove swamps intact, increasing their sizes where possible, and controlling cockle predators would lead to an increase in cockle abundance and harvests. Fishes that prey on juvenile cockles might be seined along the edges of swamps before the tide rises and they swim into the swamps to feed. Transplanting mangrove seedlings to suitable areas might increase the size of those habitats. The numbers of fishermen may increase in the future, because most adults now have several children. If new fishermen are tempted to harvest small, immature cockles and stocks are not increased, minimum size rules for harvestable cockles could be implemented and enforced to ensure adequate spawning.