Análise de dados colhidos a bordo da embarcação Cassiopeia de 7 a 15 de Maio de 1999

This paper aims to analyse the results of a cruise aboard the vessel Cassiopeia, held from 7 to 15 May 1999. These results relate mainly to the Quissico area and have as an objective to verify different features: total fish catch, predominance of caught species, dimensions of captured fish and fishing effort.

Possíveis relações entre a área de pesca, profundidade e tempo de imersão nas actividades da pesca com covos

A cruise aboard the vessel Cassiopeia was held from 14 to 22 November 2000. The objective to map the fishing areas, to study the variation of the catch, income, specific composition and length on wishbone Polysteganus coeruleopunctatus (cachucho) in relation to fishing areas, depth and immersion time of the fish pots. The total capture registered was 4.350,00 Kg for 1600 fish pots and 32 effectuated throws. The highest capture per throw was registered in the interval of depth between the 140 to 180 meters. Regarding the time of immersion, the better captures were obtained in the interval between 25 and 30 hours. The profits during this cross were for fish-trap (2, 71 kg), per throw 135,00 Kg and for immersion hour 6,07 kg. P. coeruleopunctatus (cachucho) was more abundant in number in Quissico, while in Zavora it was abundant in number and also in weight. Likewise, the cachucho was more abundant in number and weight in the captures of the fish pots submerged less than 24 hours, 100-140 meters depth. Cachucho catch under 100 meters depth was quite reduced (less than 1 %). The middle length of the cachucho captured during the cross was 275,7 mm. There were significant differences in the lengths of the cachucho accordingly to depth or fishing area. The smallest individual (fish) was captured by fish pots that were submerged more than 24 hours. The principal recommendations of the study refer to maintenance of the current fishing effort with regard to the number of fish pots, and explore the fishing areas on a rotating basis, to avoid the local effort, currently high.

Linefish resources annual report for the year 2000. Part 1: fisheries assessment

This work reflects the activities of line and trap fishing in Southern Mozambique in 2000. The catch in line fishing has been estimated at 441 mt, according to the DNAP records. The same sources indicated that 1767 days were spent at sea and the estimated catch rate was 250 Kg per boaticlay. Most of the line fishing effort shifted away from Maputo and moved to Inhambane region. The monthly analysis of fishing vessels, stricter controls over catch and effort data submission, development of long-term research programme and the continuation of the on board sampling to improve the data collection are the recommendation for line fishing. The catch of trap vessels increases from 30mt in 1997 to 172 mt in 2000, during which the total number of traps increased from 25 to 300. During this time the number of fishing days has remained relatively constant, as well the soak time. These data sets are thus not compatible with each other, reflecting an increase in daily catch from 243 Kg to 791 kg. The species composition is mainly dominated by P. coeruleopunctatus, C. puniceus, C. nufar and E. andersoni.

Bilan des recherches sur la crevette rose Penaeus duorarum notialis de Côte d'Ivoire et conséquences en matière d'aménagement

A summary of results obtained from 1969 to 1977 is given. It concerns the biology of the species (ecology and distribution of the adults, behaviour and diel variation of catch rates, reproduction and larval migration, juveniles migration and recruitment at sea, sexual maturity, growth and mortality by marking experiments) and the history of the fishery (catches, efforts, seasonal variations of catch rates). The combined use of a dynamic pool model of Ricker and a production model of Fox leads to the evaluation of the potential of the stock. The simulation of different and combined fishery strategies on adults at sea and juveniles in lagoons, allows the evaluation of the consequences (in yield, value, biomass and potential fecundity) of the different proposed management procedures (reductions in fishing effort, closed seasons on both fisheries).

La pêche au chalut en Côte d'Ivoire. Maximum de rendement économique

This paper analyses the relations between effort and catch per unit effort of trawlers which worked in Côte d'Ivoire from Jan 1966 to Dec 1970. A fishing effort permitting to exploit fishery in the best rentability conditions is proposed.

Biologie et dynamique d'un Sciaenidae ouest-africain Pseudotolithus senegalensis (V.)

In relation to the hydroclimate prevailing off Congo (B) and Côte d'Ivoire, synchronic variations are described in abundance and distribution of Pseudotolithus senegalensis V., economically the most important species in the West African trawl fishery. Although this fish prefers the warm surface layer, it is relatively indifferent to hydrological conditions, since it may also occur in the thermocline down to the higher levels of 'Central South Atlantic Water'. The oxygen concentration appears to have an important effect upon their distribution, especially the low concentrations occurring with the upwelling. The main biological functions, such as spawning and recruitment times, condition factor, diet and ring appearance on otoliths, also follow cycles, which are parallel with the hydroclimate one. Therefore, the ring-shaped structures revealed by burning previously ground otoliths could be easily interpreted. Thus, an accurate method for ageing tropical fish is now available. From the age determinations for the Congolese stock, it appears that growth is fast and total mortality rate high. An influence of fishing effort, which increased 3 times during the exploited phase of sampled specimens, appears both in growth and in total mortality. From there an estimate for the fishing mortality could be given. The estimates of dynamic parameters for the Congolese stock are then used in the Beverton-Holt model. A valuable increase of the yield could be expected, if mesh size is widened and effort restricted.

Standardisation des efforts de pêche des chalutiers ivoiriens et estimation de l'abondance relative dans les divers secteurs

The method developed by Robson (1966) is used to standardize fishing effort of Côte d'Ivoire trawlers whose size and power are very different. This method also allows the estimation of the relative abundances in the different fishing areas. The results obtained using 10 years data show that the entire Ivorian continental shelf can be considered as a single fishery unit. The relative fishing power of vessels is well correlated with gross tonnage, brake horse power and length of the vessel. The obsolescence of the trawlers affects their fishing power.

Statistiques de pêche en lagune Ebrié (Côte d'Ivoire): 1976 et 1977

In the Ebrié lagoon fishes are mostly caught by means of 6 kinds of fishing gear: small and large mesh gillnets (respectively 1.5-2 and 6.5-8 inches stretched mesh), cast-nets and multi-hooked lines for individual fishermen, and beach seines and ring-nets for collective fishing. Statistical data gathered during 1977 allowed an estimation of total catches: about 6700 tons. The bulk of the catch, 4800 tons, came from beach nets and ring nets, the contribution of which is nearly the same. Individual fishing gear, small mesh gillnets repesenting the main part, account for 25 to 30% of total catch; about 1900 tons for year 1977. Six species, or species groups, comprise more than 85% of the catch. In the Abidjan area, where marine influence is the more noticeable, ring nets are more numerous and their catches increased since 1975. On the other hand, fish captures in unsalted and brackish waters seem to show a stagnancy and a decrease in fish lengths; this phenomenon is probably in connection with beach-seine excessive fishing effort and/or their small meshes (one inch stretched).

État des stocks pélagiques côtiers en Côte d'Ivoire

Evolution of catch and catch by unit effort of the sardine fishing boats (purse seiners) has been examined from 1966 to 1975. The effort data has been calculated with a new computer programme: Crosardi (Soisson et Barbe, 1974). The analysis has been done on the whole stock and in more detail on the east and west stocks of Côte d'Ivoire. The Sardinella eba stock has been analysed separately. Those analyses were done using the general production model (Prodfit; Fox, 1974). The stock of the eastern area of the Côte d'Ivoire seems to be exploited at its maximum level. Nevertheless, the western area stock could be able to support a progressive increase of fishing effort.

1991 fisheries statistics, Lake Kariba - Zimbabwe shore

This statistical report covers catch records from the Zimbabwe part of Lake Kariba for the period 1974-1991. Landings, catches and fishing effort statistics are included for both the kapenta and the inshore artisanal fishing sectors.

1992 fisheries statistics, Lake Kariba - Zimbabwe shore

This statistical report covers catch records from the Zimbabwe part of Lake Kariba for the period 1974-1992. Landings, catches and fishing effort statistics are included for both the pelagic and the inshore artisanal fishing sectors.

1993 fisheries statistics, Lake Kariba - Zimbabwe shore

This statistical report covers catch records from the Zimbabwe part of Lake Kariba for the period 1974-1993. Landings, catches and fishing effort statistics are included for both the kapenta (pelagic) and the inshore artisanal fishing sectors.

Analysis of sex-specific spawning biomass per recruit of the sailfish (Istiophorus platypterus) in the waters off eastern Taiwan

Analyses of sex-specific yield per recruit and spawning stock biomass per recruit were conducted to evaluate the current status of the sailfish (Istiophorus platypterus) fishery in the waters off eastern Taiwan. Natural mortality rates estimated from Pauly’s empirical equation were 0.26/yr for females and 0.27/yr for males. The current fishing mortality rates were estimated as 0.24/yr and 0.43/yr for females and males, respectively, which are much lower than the estimated F0 .1 (0.62/yr and 0.79/yr for females and males, respectively) and FSSB40 (0.46/yr for females) which are commonly used as target reference points in fisheries management. The effects of the fishing mortality, natural mortality, and age at first capture on the estimates of biological reference points were evaluated by using the Monte Carlo simulation. The results indicate that failure to consider the uncertainty in parameters such as natural mortality or age at first capture may lead to the improper estimation of biological reference points. This study indicates the possibility of current fishing mortality exceeding the target biological reference points may be negligible for sailfish in the waters off eastern Taiwan. However, in view of the recent rapid increase in fishing effort, it is evident that the stock status and development of the fishery need to be closely monitore

Use of non-natal estuaries by migratory striped bass (Morone saxatilis) in summer

For most migratory fish, little is known about the location and size of foraging areas or how long individuals remain in foraging areas, even though these attributes may affect their growth, survival, and impact on local prey. We tested whether striped bass (Morone saxatilis Walbaum), found in Massachusetts in summer, were migratory, how long they stayed in non-natal estuaries, whether observed spatial patterns differed from random model predictions, whether fish returned to the same area across multiple years, and whether fishing effort could explain recapture patterns. Anchor tags were attached to striped bass that were caught and released in Massachusetts in 1999 and 2000, and recaptured between 1999 and 2007. In fall, tagged striped bass were caught south of where they were released in summer, confirming that fish were coastal migrants. In the first summer, 77% and 100% of the recaptured fish in the Great Marsh and along the Massachusetts coast, respectively, were caught in the same place where they were released. About two thirds of all fish recaptured near where they were released were caught 2–7 years after tagging. Our study shows that smaller (400–500 mm total length) striped bass migrate hundreds of kilometers along the Atlantic Ocean coast, cease their mobile lifestyle in summer when they use a relatively localized area for foraging (<20 km2), and return to these same foraging areas in subsequent ye

The western blue groper (Achoerodus gouldii), a protogynous hermaphroditic labrid with exceptional longevity, late maturity, slow growth, and both late maturation and sex change

The western blue groper (Achoerodus gouldii) is shown to be a temperate protogynous hermaphrodite, which spawns between early winter and mid-spring. Because A. gouldii changes body color at about the time of sex change, its color can be used as a proxy for sex for estimating the size and age at sex change and for estimating growth when it is not possible to use gonads for determining the sex of this fish. The following characteristics make A. gouldii highly susceptible to overfishing: 1) exceptional longevity, with a maximum age (70 years) that is by far the greatest yet estimated for a labrid; 2) slow growth for the first 15 years and little subsequent growth by females; and 3) late maturation at a large total length (TL50 = 653 mm) and old age (~17 years) and 4) late sex change at an even greater total length (TL50 = 821 mm) and age (~35 years). The TL50 at maturity and particularly at sex change exceeded the minimum legal total length (500 mm) of A. gouldii and the lengths of many recreationally and commercially caught fish. Many of these characteristics are found in certain deep-water fishes that are likewise considered susceptible to overfishing. Indeed, although fishing effort for A. gouldii in Western Australia is not particularly high, per-recruit analyses indicate that this species is already close to or fully exploited.