El estado actual de los tiburones y rayas sujectos a explotación comercial en el Golfo de California: una investigación aplicada al mejoramiento de su manejo pesquero y conservación

Se realizaron prospecciones estacionales durante 1998–1999 en Baja California, Baja California Sur, Sonora y Sinaloa para determinar la dimensión y las actividades de las pesquerías artesanales de elasmobranquios dentro del Golfo de California. Ciento cuarenta y siete campamentos o sitios pesqueros fueron documentados, la mayoría de los cuales (n= 83) fueron localizados en Baja California Sur. Entre los campamentos con información pesquera adecuada, la gran mayoría (85.7%) pescaron elasmobranquios en algún momento del año. La mayoría de los pequeños tiburones y rayas demersales fueron capturados en pesquerías multiespecíficas, las cuales también tienen como objetivo teleósteos, pero los grandes tiburones fueron capturados generalmente por pesquerías de redes agalleras a la deriva dirigidas a ellos, o en menor grado, por pesquerías de palangre de superficie. Los pescadores artesanales presentaron un comportamiento altamente oportunístico y temporalmente cambiaban de especie objetivo dependiendo de la productividad de los recursos pesqueros locales de especies de escama, invertebrados y elasmobranquios. Las mayores pesquerías de pequeños tiburones (≤1.5 m, “cazón”) se documentaron en Baja California, Sonora, y Sinaloa durante la primavera y adicionalmente durante otoño e invierno en Sonora. Los tiburones del genero Mustelus (Mustelus spp) dominaron los desembarques de cazón en los estados norteños, mientras que los tiburones martillo juveniles (Sphyrna lewini) sostuvieron la pesquería en Sinaloa. Los grandes tiburones (> 1.5 m, “tiburón”) fueron componente menor de las pesquerías artesanales de elasmobranquios en Sonora y Sinaloa, pero comúnmente fueron capturados en verano y principios de otoño en Baja California y Baja California Sur. El tiburón zorro pelágico (Alopias pelagicus) y el tiburón piloto (Carcharhinus falciformis) fueron comúnmente desembarcados en Baja California, mientras que un diverso ensamble de tiburones pelágicos y grandes costeros fueron observados en los desembarques de Baja California Sur. Las rayas dominaron los desembarques en verano en Baja California y Sinaloa, sostenidas principalmente por elevadas tasas de captura de la guitarra común (Rhinobatos productus, 13.2 individuos/embarcación/viaje) y del tecolote (Rhinoptera steindachneri, 11.1 individuos/embarcación/viaje). La pesquería de rayas de Sonora fue la más extensamente documentada durante este estudio y las rayas (especialmente R. productus) dominaron los desembarques en primavera y verano en este estado. Las tasas de captura estacionales de pequeños tiburones demersales y rayas fueron considerablemente mayores en Sonora que en los otros estados prospectados. Numerosas poblaciones de tiburón (p. ej. C. leucas, C. limbatus, C. obscurus, Galeocerdo cuvier) han sido probablemente sobreexplotados, lo que posiblemente este causando un cambio en el esfuerzo hacia las poblaciones de cazón y rayas costeros. Se proponen recomendaciones de manejo, incluyendo conducir análisis demográficos empleando la información de historias de vida disponible, localizando y protegiendo áreas de crianza e implementando temporadas de veda estacional en las áreas de mayor concentración de elasmobranquios (p. ej. alimentación, reproducción). Sin un manejo pesquero efectivo, vigilado, para sostener o reconstruir las poblaciones de elasmobranquios sujetas a explotación comercial dentro del Golfo de California, el colapso de las pesquerías es un evento probable. (PDF contains 261 pages)

Reproduction et fécondité du machoiron Chrysichthys nigrodigitatus en élevage

Different rearing facilities (concrete tanks, pens and ponds) were tested for suitability as spawning environments. The concrete tanks and the pens in the lagoon gave the best results as to the number of spawns obtained. Of the three types of spawning devices tested, containers with a 150 mm opening at one of the two ends were preferably used by the fish. The brooders in the spawning facilities spontaneously entered the spawning containers to deposit their eggs without external human intervention. Actual fecundity estimates ranged from 9805 to 40597.

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.

Estado actual das principais pescarias da Baia de Maputo

This report presents an analysis of existing information on fisheries of shad and shrimp. It explains the use of Schaefer model and based on this and other available information, the author suggests the measures to be implemented for a better management of these resources.

Estado actual da pescaria de camarāo no Banco de Sofala

A summary of the shrimp fishery history as well as the most important recommendations for the period 1977-1990 is presented. During the last years the catch rates have decreased. Although many possible causes can be appointed, such as, weather conditions and increase of effort, there is no clear explanation for it. A relationship between catch rates in the main period of recruitment (January to March) and the level of recruitment of the same year was established. Based on this relationship, the total annual catch is predicted for the level of fishing mortality chosen. Fishing mortality is estimated as 2.28 yearˉ¹ and a gradual reduction of fishing effort is recommended until 2.17 yearˉ¹ calculated as F(sub)0.1.

Poverty in the fisheries, inductors, causes and intervention

The study is prompted by the poverty that persisted among the fishing communities of lake victoria at time of considerable cash inflow into the fisheries development of fish processing industry. There has been need for understanding of the poverty and what strategies would be most appreciate for it's reduction.This study has attempted to respond to the needby identifying the nature and distribution of the poverty within the fisheries lake victoria,Uganda, the factor responsible for itand the options for poverty reduction intervention. The study examined the global and regional perspectives of poverty and wealth distribution, noting that wide disparities existed between the developed and the developing world and also between the developing countries themselves. A historical review of development policies and strategies revealed that while successive strategies were able to contribute to growth, their achievement towards poverty alleviation were less than satisfactory, hence the need for continually developing new strategies. A background to Uganda’s society and economy is provided, examining the demographic, political, environmental and economic conditions of the country. Uganda’s development strategies are reviewed, highlighting the role of the Poverty Eradication Action Plan, Uganda’s main strategy for implementing the policy of poverty reduction and wealth distribution. At the agricultural sector level, the Plan for the Modernisation of Agriculture has been formulated, followed by the National Fisheries Policy, aimed at providing a policy framework for the management and development of the fisheries. An appropriate definition of poverty was formulated, considered relevant to the situation of Lake Victoria. The dimensions of poverty included inadequate basic necessities, low education and health achievements, a sense of insecurity and exposure to risk. The research methodology was enhanced by the examination of the Lélé Model of the Poverty–Environmental Degradation problem, the World Bank Model of Poverty Causation and the subsequent Lake Victoria Model developed in this study. It has provided a plan for the research, the consideration of criteria and a data collection plan. The data collection instruments included secondary data search, key informant interviews and a sample survey based on a structured questionnaire. The study identified all the four dimensions of poverty in the fisheries, provided poverty profiles with respect to the different activities, groups of people and regions in the fisheries, based on consumption poverty. Among the people identified to be in poverty were the fishing labourers, fishers of Oreochromis niloticus and those operating with non-powered boats. In the post-harvest fisheries, large proportions of processors involved in salting and sun-drying, market stall and bicycle traders were in the poverty category. The ethnic groups most affected included the Samia, Basoga and Bakenye while the Districts of Jinja, Bugiri and Busia had the highest proportions of fishers in the poverty category. With respect to the other dimensions of poverty, the study showed that educational achievement was low within the fishing communities. The health status was poor, due mainly to the prevalence of malaria, diarrhoea, bilharzia and HIV/AIDS. There was a sense of insecurity within certain sections of the fishing community, due to leadership weaknesses within the local as well as the Government institutions. Some community members operated in a state of risk because they were vulnerable to episodes of income, health and education. The causes of poverty in fisheries included weaknesses within the institutional and social environment, limitations in the technology available to the poor, resource degradation and unfavourable economic factors. The recommendations of the study for poverty reduction included strengthening of policies, developing links, improving capacities and increasing resources, to be applied at the levels of Central Government, Local Government and of the community. In view of the achievements of the methodology used on this study, involving reference to the models, it is recommended that future research should build upon this model approach, as it will continue to produce results, especially when attempting to forecast changes relating to interventions.