Synopsis of biological data on the porgies, Calamus arctifrons and C. proridens (Pisces: Sparidae)

Information on the biology and fishery resources of two common species of western Atlantic porgies, Calamus areli/rons and C. proridens, is compiled, reviewed, and analyzed in the FAO species synopsis style. (PDF file contains 25 pages.)

Review of geographical stocks of tropical dolphins (Stenella spp. and Delphinus delphis) in the eastern Pacific

Information on geographical variation is reviewed for Stenella attenuata, S. longirostris, S. coeruleoalba, and Delphinus delphis in the eastern tropical Pacific, and boundaries for potential management units are proposed. National Marine Fisheries Service and Inter-American Tropical Tuna Commission sighting records made from 1979 to 1983 which were outside boundaries used in a 1979 assessment were examined for validity. Tagging returns and morphological data were also analyzed. Several stock ranges are expanded or combined. Three management units are proposed for S. attenuata: the coastal, northern offshore, and southern offshore spoiled dolphins. Four management units are proposed for S. longirostris: the Costa Rican, eastern, northern whitebelly, and southern whitebelly spinner dolphins. Two provisional management units are proposed for S. coeruleoalba: the northern and southern striped dolphins. Five management units (two of which are provisional) are proposed for D. delphis: the Baja neritic, northern, central, southern, and Guerrero common dolphins. Division into management units was based on morphological stock differences and distributional breaks. (PDF file contains 34 pages.)

Annual report chinook salmon spawner stocks in California's central valley, 1991

This report covers the 39th annual inventory of chinook salman, Oncorhynchus tshawytscha, spawner populations in the Sacramento-San Joaquin River system." It is a compilation of reports estimating the fall-, winter-, late-fall-, and spring-run salman spawner populatiens fer streams which were surveyed. Estimates were made from counts of fish entering hatcheries and migrating past dams, from surveys of dead and live fish and redds on spawning areas, and from aerial counts. The estimated 1991 total escapement of chinook salmon in the Central Valley was 147,080 fish. This total consisted of 132,571 fall-, 5,921 spring-, 190 winter-, and 8,398 late-fall-run spawners. All of the spring-, late-fall-, and winter-run salmon were estimated to be in the Sacramento River system, while 1,176 fish of the fall run were in the San Joaquin River system. Spawner populations in all individual tributaries (except the American River) and the Sacramento River mainstem were lower than in 1990; but it should be noted that fall run populations in the Feather and Yuba rivers, two of the larger tributaries, were not surveyed that year. The winter run in the mainstem Sacramento River was at a record low level. (PDF contains 42 pages.)

Seasonal water quality monitoring in the Klamath River estuary, 1991-1994

The California Department of Fish and Game's Natural Stocks Assessment Project (NSAP) collected water quality data at high tides on a monthly basis from February 1991 to October 1994, and during low tides from March 1992 to June 1994 in the Klamath River estuary to describe water quality conditions. NSAP collected data on water temperature, dissolved oxygen, salinity, depth of saltwedge, and Klamath River flow. Klamath River flows ranged from 44.5 cubic meters per second (1570 cfs) in August 1994 to 3832.2 cubic meters per second (135,315 cfs) in March 1993. Saltwater was present in the estuary primarily in the summer and early fall and generally extended 2 to 3 miles upstream. Surface water temperatures ranged from 6-8° C in the winter to 20-24° C in the summer. Summer water temperatures within the saltwedge were generally 5 to 8° C cooler than the surface water temperature. Dissolved oxygen in the estuary was generally greater than 6 to 7 ppm year-round. A sand berm formed at the mouth of the river each year in the late summer or early fall which raised the water level in the estuary and reduced tidal fluctuation so that the Klamath estuary became essentially a lagoon. I hypothesize the formation of the sand berm may increase the production of the estuary and help provide favorable conditions for rearing juvenile chinook salmon.

Recovery of the stocks of the European eel (Anguilla anguilla) by spawner enhancement

The production of healthy high quality female European eel in recycle systems is proposed as a means to secure sufficient numbers of silver eel for spawning migration in order to meet the requirements of the European Commission’s proposal for a Regulation for the recovery of the stock of the European eel. Main advantages besides checks for parasites and viral diseases and avoidance of elevated levels of specific pollutants are the easily controllable numbers of spawners to be released and a reduction of labour and costs that will occur when acting along the lines of the Commission’s proposal.

Morphometric comparison of skipjack from the Central and Eastern Tropical Pacific Ocean

ENGLISH: One of the important problems in the current investigations of the Inter-American Tropical Tuna Commission is the determination of the racial affinities of the stocks of yellowfin and skipjack inhabiting the Eastern Tropical Pacific fishing region. The nature of the problem is twofold. Primary concern is elucidation of the inter-regional relationship of stocks between the Eastern Tropical Pacific fishing region and those further to the westward. Hardly less important, however, is the intraregional relationship of stocks within the regions, particularly the Eastern Pacific region. This latter relationship must be at least partially understood in order properly to approach investigation of the former. SPANISH: Dentro de las las investigaciones que al presente efectúa la Comisión Interamericana del Atún Tropical, uno de los importantes problemas consiste en la determinación de las afinidades raciales de los stocks de atún aleta amarilla y barrilete que se encuentran en las regiones de pesca del Pacífico Oriental Tropical. La naturaleza del problema es doble. El interés primario es la elucidación de la relación inter-regional entre los stocks de la región pesquera del Pacífico Oriental Tropical y los de aquéllas más hacia el oeste de dicho océano. Apenas menos importante, sin embargo, es la relación intra-regional de los stocks dentro de las regiones, particularmente la del Pacífico del Este. Esta última relación debe ser por lo menos parcialmente conocida, a fin de abordar con propiedad la anteriormente citada. (PDF contains 63 pages.)

ICES-Arbeitsgruppentreffen zum "Lebenszyklus und Fischerei von Nordseegarnelen" (WGCRAN)

Two years after their last meeting, scientists from North Sea neighbouring countries working on aspects of brown shrimp biology and fisheries gathered in Oostende, Belgium, to exchange information and results of their research. The group was established ten years ago by the International Council of the Exploration of the Sea (ICES)during the Warnemünde Annual Science Conference. Data on brown shrimp landings, fishing effort and resulting landings per unit effort were compiled. For the first time a computer model was demonstrated simulating the life cycle of C. crangon on basis of experimental and field data available. It will provide a means for testing different possible scenarios and their effect on the brown shrimp stocks. Catch predictions are not possible by this, as no stock assessments can yet be achieved for brown shrimp, and a number of topics have to be addressed by further research programmes. However, an approach of estimating the level of landings on basis of preceding climatological and hydrographical data seemed promising. Furthermore selectivity experiments and electric gear types were reported giving reason to assume, that progress is possible in the further reduction of bycatches. The assembling of already existing data in various countries and their evaluation was recommended besides the pursuing of the mentioned fields of research and proper reporting of EU log book data by all countries.

Effects of human chorionic gonadotropin (HCG), toad and Clarias pituitary hormogenates on spawning in the catfish: Clarias Lazera (C. and V.) and Clarias anguillaris (Linne)

Experiment on induced spawning of Clarias lazera and C. anguillaris using human chorionic gonadotropin (HCG) freshly prepared toad and Clarias pituitary hormogenates were carried out. Clarias pituitary hormogenates induced spawning in C. lazera and C. anguillaris at dosage levels of 0.27-0.46 mg/150 g body weight or 2 glands/fish of equivalent weights. HCG induced spawning in C. anguillaris at 500 i.u/500 g body weight but failed in C. lazera. Toad pituitary was not successful at even a higher dosage level of 0.60 mg/150 g body weight. The implications of these results are discussed. Spawning occurred in the HCG (and Clarias pituitary treated females in less than 12 hours after injection and subsequent examination of ovaries of the spawned fish showed incomplete spawning. Furthermore, fertilization occurred, following spawning in the piscine pituitary hormone treated male and female fish but failed in the HCG (treated pair. A mean fertilization rate of 50-90% was recorded. Possible explanations of these observations are advanced. The hatching time of 24-48 hours and a mean hatching rate of 75-90% were recorded. A high larval mortality of up to 95% was observed in the post yolk-sac stag after 8 days. The need for the development of appropriate larval food for Clarias species in culture practice is stressed

A study on the growth of Pseudotolithus elongatus, Chrysichthys nigrodigitatus and Cynoglossus goreensis occurring in the Cross River Estuary

Samples of Pseudotolithus elongatus, Chrysichthys nigrodigitatus and Cynoglosus goreensis obtained from the Cross River Estuary (which is most probably the largest estuary water system along the coast of West Africa) between January 1980 and May 1981 were evaluated on basis of population dynamic analytical method postulated by Pauly (1980) for tropical fish stocks. Growth parameters were obtained for the fish species. Wherever possible, these results were compared to those obtained by Longhurst (1964d) and LeGuen (1971) in other West African waters. On the whole, results obtained in this study tend to indicate that the growth of the croaker, bagrid catfish and the sole in the Cross River Estuary is allometric, the third and fourth year-classes of P. elongatus the second and third class-year of C. nigrodigitatus and the fourth, fifth and sixth year classes of C. goreensis dominated in the age distribution of these fish species

Induced spawning of African cat fish Clarias lazera (C. and V.) using acetone dried carp pituitary extract, deoxy-corticosterone acetate and human chorionic gonadotropin

A study was conducted to determine the efficacy of carp pituitary extract, deoxycorticosterone acetate, and human chorionic gonadotropin in inducing spawning in Clarias lazera . Results indicate deoxycorticosterone acetate to be more potent than pituitary extract, although the difference is not significant

Lead accumulation by hammerhead shark, Sphyrna couardi (C.) off Lagos coast, Nigeria

Levels of concentration of lead in the hammerhead shark, Sphyrna couardi, off the Lagos Coast of Nigeria were investigated. The standard length of the specimens examined ranged from 31.4cm to 47.2cm while the weights ranged from 451.5 to 1,667g. The lead concentration ranged from 0.11 degree kg/G to 0.38 degree kg/G. The mean lead concentration was 0.56 degree kg/G (dry weight). The gill has the highest lead concentration. There was no linear correlation between the length and weight and the amount of lead concentrated

Recent trends in the distribution patterns and catch rates from trawl surveys in Lake Victoria, Tanzania

Trawl surveys to assess the stocks of Lake Victoria (Tanzania) for estimates of biomass and yield, together with the establishment of exploitation patterns, are being undertaken under the Lake Victoria Fisheries Research Project. Preliminary surveys to establish the sampling stations and strategy were carried out between October 1997 and February 1998. Three cruises to cover the whole of Tanzanian waters were undertaken with 133 sampling stations. Data on each rates, species composition, and distribution were collected. Three sampling areas were designated: area A, B and C. In each area, almost the same distribution pattern over depth was found. Lates niloticus (L) formed over 90% of the total catch. Most L. niloticus were from 5-40 cm TL. Abundance decreased with depth, few fish were found deeper than 40m and most fish were caught at <20 m deep. Catch rates varied considerably between stations and areas. Area A had the highest catch rates with little variation over the stations. There is an indication of recovery of species diversity compared with the surveys of RV Kiboko(1985 and 1989)

The fish stocks of Lake Victoria, Uganda

An experimental bottom trawl survey was carried out in the Uganda sector of Lake Victoria from November 1997 to December 1998 to estimate the composition, distribution, and abundance of the major fish species. In 12 cruises, 295, thirty-minute hauls were taken in waters from 4-60 m deep. Nile perch, Lates niloticus (L) made up 95% of the catch by weight. Haplochromine cichlids and L. niloticus occurred in all areas sampled while Nile tilapia, Oreochromis niloticus (L.) and other tilapiines were restricted to waters less than 30 m deep. In waters deeper than 40 m, catches were generally near zero. Species diversity and abundance decreased with increasing water depth. In waters less than 30 m deep, the area where the artisanal fishermen operate, the mean catch was 126kg hr super(1)

Length-weight relationship and organ indices of pond raised and wild population of C. gariepinus (Burchell 1822) pisces-Claridae

Samples of C. gariepinus collected from the wild and cultured populations in Plateau and Niger States of Nigeria were analyzed for length-weight relationship and organ indices (Gonadosomatic index (GSI), hepatosomatic index (HSI), renalsomatic index (RSI) and somatic fat deposit index (PDI). High correlation and linear relationship between body length and body weight was observed in all sample population (P<0.05). A significant difference was observed between the GSI of males and females of both wild and cultured population and also between females of the wild and cultured population,(P < 0.05).There was no significant difference in HSI, CSI RSI and PDI of all the sample populations (P < 0.05).The importance of length-weight relationship and organ indices in fish production are discussed

Investigation of nematode Eustrongylides larvae infections in mudfish Clarias gariepinus and C. anguillaris from Bida floodplain of Nigeria

This is the first report and record of the determination whether mudfish Clarias were infected with the larvae of the nematode Eustrongylides. Also, documented the assessment of the socio-economic perceptions of three groups of fisher folks on the economy of infected mudfish Clarias fishing activities. Fifty-six (67.5%) of 83 mudfish Clarias caught by artisanal fisher folks were examined for the presence of the larvae of the nematode Eustrongylides. All the 8 sampled fishing localities in Bida floodplain of Nigeria had a mean intensity and abundance of at least 3 and 1 worm per fish per site, respectively. Two hundred and one (96.2%) of 209 worms recovered were from the musculatures at different depths resulting in undulations on the skin surfaces as grub-like presentations. The three groups of fisher folks assessed encountered economic losses from nematode infected mudfish Clarias which attract much debates or rejections during marketing due to its aesthetically displeasing appearance, faster deterioration, higher fragility in smoked form coupled with poorer taste compared to the wholesome ones. Infected female mudfish Clarias had higher worm burden than the males, for each fishing locality