Simulated and Actual Effects of the Brown Shrimp, Penaeus aztecus, Closure in Mexico

Simulations based on a yield-per-recruit model were performed to analyze the impact ofg rowth overfishing on brown shrimp, Penaeus aztecus, and to assess the effects of a closed season inshore and offshore of the Mexican States of Tamaulipas and Veracruz. Closure of both the inshore and offshore fisheries could enhance cohort yield by more than 300%. Cohon yield enhancement would be only about 60-80% if only the offshore season were closed. The closed season of 1993 gave better results as it covered a larger part of the brown shrimp peak recruitment period. Catch per unit of effort (CPUE) after closure in 1993, compared with 1994, was 2.4 times higher than the mean CPUE of the month. Total annual offshore yield increased 72% in 1993 (3,800 metric tons (t)) and 10% in 1994 (506 t) with respect to the mean annual offshore catch during the 10-year period prior to the 1993 closure. Simulation results could help identify alternatives that permit the coexistence of the inshore and offshore fisheries while maintaining high profitability of the brown shrimp fishery.

An Economic Analysis of Texas Shrimp Season Closures

Management of the Texas penaeid shrimp fishery is aimed at increasing revenue from brown shrimp, Penaeus aztecus, landings and decreasing the level of discards. Since 1960 Texas has closed its territorial sea for 45-60 days during peak migration of brown shrimp to the Gulf of Mexico. In 1981 the closure was extended to 200 miles to include the U.S. Exclusive Economic Zone. Simulation modeling is used in this paper to estimate the changes in landings, revenue, costs, and economic rent attributable to the Texas closure. Four additional analyses were conducted to estimate the effects of closing the Gulf 1- to 4-fathom zone for 45 and 60 days, with and without effort redirected to inshore waters. Distributional impacts are analyzed in terms of costs, revenues, and rents, by vessel class, shrimp species, vessel owner, and crew.

Impact of the commercial fishery on the population of bait shrimp (Penaeus spp.) in Biscayne Bay, 1986

Monthly population size of bait shrimp in the Bay was estimated from December 1984 to July 1985. Growth rates for male and female P. duorarum showed that pink shrimp exhibit a mean residence time in the nursery area (Biscayne Bay) of approximately 21 weeks. Monthly mortality rates were determined for each sex of pink shrimp. It was estimated that 23% and 26% of the male and female monthly population size, respectively, was absorbed by both the fishery and ecosystem monthly. Monthly proportion of the standing stock expected to die exclusively through fishing was 6.5% and 6.0% for males and females respectively. Estimates of emigration rates showed that approximately 4.0% of the population was lost from the Bay system each month. This surplus production was about 50% of the average monthly catch by the fleet. Fishing mortality represents only 8 - 9% of the losses to the shrimp population. The biggest source of loss is emigration, suggesting that most shrimp beyond the size at recruitment (to the fishery) are not utilized for food while in the Bay. Thus, it appears that the direct impact of the fishery on the bait shrimp population is relatively small. (PDF contains 46 pages)

Design, operation and economics of a small-scale hatchery for the larval rearing of sugpo, Penaeus monodon Fab.

One of the major problems in the mass production of sugpo is how to obtain a constant supply of fry. Since ultimately it is the private sector which should produce the sugpo fry to fill the needs of the industry, the Barangay Hatchery Project under the Prawn Program of the Aquaculture Department of SEAFDEC has scaled down the hatchery technology from large tanks to a level which can be adopted by the private sector, especially in the villages, with a minimum of financial and technical inputs. This guide to small-scale hatchery operations is expected to generate more enthusiasm among fish farmers interested in venturing into sugpo culture.

Size composition of the catches of the pink shrimp Penaeus duorarum notialis in the shrimp fishery of Sierra Leone

Measurements were taken of size distribution of P. d. notialis collected off Sierra Leone over a period of six months from October 1977 to March 1978. From the frequency distribution curves it is observed that the curves for male shrimps show only one or two major modes, which show prominence between 12.5 and 14.1 cm of total length. Females mostly exhibited size groups with three or four different length ranges and occasional occurrence of 1 to 5 modes. These size groups were observed to show continuous changes. No one group could be said to be permanent. The point of entry into the fishery of male shrimps was found to be at an average total length of 10.5 cm, while females did so at 11 cm. Sex ratios in the different samples were usually 1:1 but in one case the males were more numerous by 2:1 and in four other samples females were significantly preponderent. These departures from the 1:1 ratio may have been artificially created by sorting of the catches on board the ships.

Penaeus indicus H. Milne Edwards, 1837: resumo das conclusões dos cruzeiros de pesca exploratória entre 1979 e 1983 no banco de Sofala em Moçambique

From 1979 to 1983, several surveys were carried out with research and fishing vessels at Sofala Bank in Mozambique. Their main objective was the assessment of shallow water prawn stocks, as this resource is of great economic importance for the country. A summary of the conclusions of these surveys regarding the species Penaeus indicus is presented. During the rainy season the species occurs closer to the shore than during the dry season. Estimates of biomass are very variable. The spawning peak seems to occur at the beginning of the rainy season (September-October). The spawning areas are located very close to the shore in the northern part of Sofala Bank and South of 17 degree 10'S in the 15-25 m depth interval.

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).

Biologie de Penaeus duorarum (Burkenroad) en Côte d'Ivoire: croissance

The Petersen method was used to make growth assessments from experimental data collected during 1966-67 and 1969-70. The parameters K and L ∞ were calculated from the Von Bertalanffy growth curve. There was very little difference between the two years although growth in 1969 appeared slightly greater. A comparison of our results in Côte d'Ivoire with those from Senegal and Gulf of Mexico showed that the greatest growth occured on the west African coast and especially off the Côte d'Ivoire.

Rélation longueur céphalothoracique-poids total chez Penaeus duorarum (Burkenroad) en Côte d'Ivoire

This short note gives the results of the measurements of cephalothoracic length-total weight of Penaeus duorarum in Côte d'Ivoire and compares those data to the ones collected in Senegal (Bondy 1968) and in the Gulf of Mexico (Kutkuhn 1965).

Biologie de la phase lagunaire de Penaeus duorarum en Côte d'Ivoire. Écologie et dynamique

Ecology and dynamics of juvenile pink shrimp Penaeus duorarum were studied from weekly sampling in the Abidjan lagoon system. After a brief description of biogeography and principal features of climate, hydrology of Ebrié lagoon and Adiopodoumé bay were considered. Shrimp distribution were connected with the main environmental factors. Precise work was done in Adiopodoumé bay, especially concerning the succession of age classes, their growth on the nursery grounds, seasonal variation in abundance, size and distribution, in relation to environmental factors. These results, and former knowledges, allowed us to propose a general pattern for pink shrimp life history in Côte d'Ivoire.