Frame survey (census of boats and fishing gear) Lake Kyoga and Lake Kwania (Uganda), May-June 1990

The census of a fishing industry is called a frame survey. This is a rather comprehensive term, because there are many aspects of a fishery which one might wish to know. This is illustrated by the report on the partial census executed by the ADP/FS on the southern landings of L.Kyoga during December 1988, which deals with many socio-economic aspects of fishermen's households.

A livelihoods study of farmers and fishers in Trorbek Pork Village Kandal Province

This is the report of a livelihoods study team working together with villagers from Trorbek Pork in Kandal Province, Cambodia. The livelihoods study is based on the current population census (1998) and key informant interviews: 10 to 70 villagers (50% women) representing the 140 families of Trorbek Pork Village, Kampong Kong Commune, Koh Thom District, Kandal Province. (PDF contains 40 pages)

A study of measures of population density and of concentration of fishing effort in the fishery for yellowfin tuna, Neothunnus macropterus, in the Eastern Tropical Pacific Ocean, from 1951 to 1956

ENGLISH: This study shows how the catch and effort statistics, from 1951 to 1956, of the fishery for yellowfin tuna, Neothunnus macropterus, in the Eastern Tropical Pacific Ocean, have been used to compute: (i) two indices of average population density; (ii) an index of concentration of effort on areas of greatest density of available yellowfin. These three indices were then used to determine: (i) quarterly and annual variation in each of them; (ii) the relationship between the two indices of density; (iii) the relationship of each of the indices to the number of exploited one-degree rectangles. To remove extreme sampling variation at low levels of effort, the data from all one-degree rectangles subjected to less than five logged days' fishing in a quarter were eliminated, and the computations were repeated for comparison with those of the original data. SPANISH: Este estudio da a conocer cómo las estadísticas sobre la pesca y el esfuerzo de pesca de la pesquería del atún aleta amarilla, Neothunnus macropterus, en el Océano Pacífico Oriental Tropical, durante 1951 a 1956, han servido para computar: (i) dos índices del promedio de la densidad de la población; (ií) un índice de la concentración del esfuerzo en las áreas de mayor densidad de atún aleta amarilla disponible. Estos tres índices han sido luego usados para determinar: (i) la variación trimestral y anual en cada uno de ellos; (ií) la relación entre los dos índices de densidad; (iii) la relación de cada uno de los índices con el número de rectángulos de un grado explotados. Para evitar la extrema variación del muestreo a bajos niveles de esfuerzo, se eliminaron los datos de todos los rectángulos de un grado sujetos a menos de cinco días de actividad pesquera durante un trimestre según los registros de los cuadernos de bitácora, y las computaciones se repitieron para compararlas con las de los datos originales.

Measures of population density and concentration of fishing effort for yellowfin and skipjack tuna in the eastern Tropical Pacific Ocean 1951-1959

ENGLISH: In a previous Bulletin of this Commission, Griffiths (1960) discussed two indices of population density and an index of concentration of fishing effort of bait boats for yellowfin tuna in the Eastern Tropical Pacific for the 1951-1956 period. Yellowfin and skipjack tuna occur in the same general fishing areas and many of the commercial catches are composed of a mixture of the two species. It is desirable, therefore, to extend the investigation to skipjack and to the two species combined. SPANISH:En un Boletín anterior de esta Comisión, Griffiths (1960) se refiere a dos índices de la densidad de la población y a un índice de la concentración del esfuerzo de pesca de los barcos de carnada sobre el atún aleta amarilla en el Pacífico Oriental Tropical, correspondientes al período 1951-1956. Los atunes aleta amarilla y barrilete se encuentran en las mismas áreas generales de pesca y muchas de las pescas comerciales están compuestas de una mezcla de las dos especies. Es deseable, por lo tanto, ampliar la investigación en lo que se refiere al barrilete y a las dos especies combinadas.

TUNPOP, a computer simulation model of the yellowfin tuna population and the surface tuna fishery of the Eastern Pacific Ocean

ENGLISH: Mathematical documentation of TUNP0P, an age-structured computer simulation model of the yellowfin tuna population and surface tuna fishery of the eastern Pacific Ocean, is described. Example runs of the model are presented and discussed, and the sensitivity of the model output to changes in various parameters is examined. SPANISH: Se describe la documentación matemática de TUNP0P, un modelo computador de simulación basado en la edad de la población del atún aleta amarilla y de la pesca atunera epipelágíca del Océano Pacífico oriental. Se presentan y se discuten ejemplos de las pasadas del modelo, y se examina la sensibilidad de los resultados de salida con relación a los cambios de varios parámetros. (PDF contains 47 pages.)

A Comparison of the SNP Variation in the Calcification PMCA Gene of Lottia gigantea between a Santa Barbara Population and a More Acidic Monterey Bay Population

As the atmospheric levels of CO2 rise from human activity, the carbonic acid levels of the ocean increase, causing ocean acidification. This increase in acidity breaks down the calcified bodies that many marine organisms depend upon. Upwelling regions such as Monterey Bay in California have pH levels that are not expected to reach the open ocean for a few decades. This study reviews one of the common intertidal animals of the California coast, the Owl Limpet Lottia gigantea, and its genetic variation of the plasma membrane Ca2+ ATPase (PMCA) in relation to the acidity of its environment. The PMCA protein functions in the calcification process of many organisms. Specifically in limpets, this gene functions to form its protective shell. Single-nucleotide polymorphisms (SNPs) were found among five sections of the gene to determine variation between the acidic environment population in Monterey, California and the non-acidic environment population in Santa Barbara, California. While some variation was determined, the Monterey Bay and Santa Barbara Lottia gigantea populations are not significantly distinct at the PMCA gene. Sections B, C, and D were found to be linked. Only one location in Section B was found to have an amino acid change within an exon. Section A has the strongest connection to the sampling location. Monterey individuals were seen to be more genetically recognizable, while Santa Barbara individuals showed slightly more variation. Understanding the trends of ocean acidification, upwelling region activities, and population genetics will assist in determining how the ocean environment will behave in the future.

Larval development of the spotfin tonguefish (Symphurus oligomerus Mahadeva and Munroe, 1990) (Pleuronectiformes: Cynoglossidae) from the Gulf of California, Mexico

Larval and early juvenile stages of Symphurus oligomerus are described from 24 specimens from the Gulf of California. Meristic features were 48 – 49 total vertebrae, 87–94 dorsal-fin rays, 73–77 anal-fin rays, 12 caudal-fin rays, and five hypural bones. Seven larvae and one juvenile were cleared and stained to obtain the pterygiophore formula (1-3-2-2-2) that confirmed the identification of S. oligomerus. The pigment pattern from preflexion to juvenile stage consists of three bands on the dorsal margin and two bands on the ventral margin formed by star-shaped melanophores on the left side of the body. The intestine in preflexion to postflexion larvae forms an abdominal projection that ends in a short conical appendix. The intestine is supported by three cartilaginous struts; larvae with these physical attributes are called exterilium larvae. Preflexion larvae have two elongated dorsal-fin rays, and in flexion to postflexion larvae the second to the fourth dorsalfin rays are elongate. We found an apparent connection between the size at metamorphosis of the species of Symphurus and the depth distribution range of adults such that the fish species that metamorphose at a larger size have a deeper distribution as adults and exterilium larvae seem to correspond to species that have deeper distributions.

Determination of population structure and stock composition of chum salmon (Oncorhynchus keta) in Russia determined with microsatellites

Variation at 14 microsatellite loci was examined in 34 chum salmon (Oncorhynchus keta) populations from Russia and evaluated for its use in the determination of population structure and stock composition in simulated mixed-stock fishery samples. The genetic differentiation index (Fst) over all populations and loci was 0.017, and individual locus values ranged from 0.003 to 0.054. Regional population structure was observed, and populations from Primorye, Sakhalin Island, and northeast Russia were the most distinct. Microsatellite variation provided evidence of a more fine-scale population structure than those that had previously been demonstrated with other genetic-based markers. Analysis of simulated mixed-stock samples indicated that accurate and precise regional estimates of stock composition were produced when the microsatellites were used to estimate stock compositions. Microsatellites can be used to determine stock composition in geographically separate Russian coastal chum salmon fisheries and provide a greater resolution of stock composition and population structure than that previously provided with other techniques.

Census of Active Commercial Fishermen in Puerto Rico: 2008

The implementation of Puerto Rican Regulation No. 6768, which overhauled the existing fishery management framework, generated considerable hostility towards local managers. Among the controversial management measures adopted in 2004 were the assignment of fishing licenses based on fishing income, the establishment of closed seasons, and new minimum size restrictions for commercially valuable species. Though tensions have subsided, considerable opposition to these regulations remains. This paper provides a characterization of the current population of active small-scale fishermen, discusses their perceptions about the biological and socio-economic condition of the fishery, and describes their attitudes towards the new management framework. This study revealed that the number of active fishermen decreased from 1,731 in 1988 to 868 in 2008. Although a declining resource base was one of the main drivers behind these waning participation statistics, rising fuel costs and burdensome regulations exacerbated the rate of attrition. The majority of the fishermen were middleaged men (50 years) with moderate levels of formal education and high levels of fishing dependence which limited their employment opportunities outside the fishery. Most of the vessels were small (20 ft) and outfitted with a single outboard engine (80 hp). Hook and line and SCUBA were dominant gears because of their versatility and cost effectiveness. Fishermen suggested that their opposition to the regulations would continue unless they were afforded greater regulatory flexibility and provided with a larger role in the decision-making process. Fishermen were adamant about the need to reconsider the income reporting requirements to secure a fishing license because of the potential for losing public assistance benefits. They also objected to increasing the minimum size of many deepwater snapper (Lutjanidae) and grouper (Serranidae) species because it forced them to discard dead fish, a practice they consider wasteful since these species do not survive the ascent to the surface once hooked.

Impact of Bashundhara Baridhara Housing Project on the status, abundance and species diversity of fish in Bashundhara Housing lake in Dhaka, Bangladesh

A study on the status of fisheries and environmental impact assessment (EIA) was conducted on Bashundhara Baridhara Housing Project (BBHP), Dhaka, Bangladesh for prediction and measure the effects of housing project related development activities that have already been implemented and planned for future implementation. The project is still under development phase and so far allotted 10,000 plots of different sizes. The study shows that the original water bodies and natural fish production there from have greatly declined due to earth filling carried out for development of land for the housing. The physico-chemical parameters of the existing water body within the project area were found to be suitable for fish farming in the estate. A number of economically important fish species are found available in the existing lake. However, the natural fisheries resources of the existing lake is under great stress due to the changes made in the ecosystem, siltation, construction of building and dumping of house building and household waste materials. This has caused some important fish species of the lake to become critically endangered and vulnerable which have been documented in this paper. Appropriate regulatory and mitigating measures with respect to water management, disposal of construction garbage and other biomedical toxic substances far away from the water bodies are required to be taken to keep the water safe and suitable for fish production as well as for multipurpose use of the lake water.

Dynamics of parasite population and its histopathological and histophysiological effects in the stomach of a freshwater fish

The caryophyllaeid cestode Lytocestoides fossilis infects the freshwater catfish Heteropneustes fossilis. The study was conducted for two consecutive years (2004-06) to record the bio-statistical data of the parasite. The incidence, intensity, density and index of infection of the parasite have been recorded. The infection was more during June to September, moderate during February to May and low during October to January. The parasite brought about severe histopathological changes in the stomach of infected fish. The changes observed in the stomach of fish included structural damage of the villi, inflammation, and fibrosis associated with hyperplasia and metaplasia. The hypertrophy of mucous layer led to vacuolation and necrosis. Histochemical changes were noticed with enhanced carbohydrate, protein and lipid contents. The enhanced substrate content in the infected organ might be due to the disfunctioning of the digestive tract, which results in the accumulation of various metabolites. Mucus secretion was triggered as a protective interaction against parasitic invasion. The parasitic infection affects the general metabolic state of the host and as the result, the fish becomes sluggish and moribund.

Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal: an assessment of population risk and data gaps for more effective regional management

Assessment of country status papers on hilsa fisheries presented at the BOBP – IGO Chittagong, Bangladesh 2010. Assessment of status hilsa management in Bangladesh, India and Myanmar. Brief recommendations of potential follow-up activities that could enhance management. Risk assessment of hilsa in each country with Productivity Susceptibility Analysis (PSA). Summary of new approach to assess ecological risk.