Statistics of the Eastern Pacific Ocean tuna fishery, 1979 to 1992

ENGLISH: This report, published in response to the large volume of requests for information received by the IATTC, provides information on the catches, effort, and composition of the purse-seine and baitboat fleets which fished for tunas and tuna-like species in the eastern Pacific Ocean (EPO) in the 1979-1992 period. It does not include data for longline fisheries operating in the EPO; that information may be found in the IATTC's Annual and other reports. The IATIC has published similar data for other periods in its Bulletin series (Shimada, 1958; Alverson, 1959, 1960, ~963; Martin, 1962; Calkins and Chatwin, 1967, 1971; Calkins, 1975; Orange and Calkins, 1981) and in its weekly, quarterly, and annual reports. SPANISH: El presente informe, publicado como resultado del gran volumen de solicitudes de información recibidas por la CIAT, presenta información sobre las capturas, el esfuerzo, y la composición de las flotas que pescaron atunes y especies afines con red de cerco o carnada en el Océano Pacífico oriental (OPa) en el período de 1979-1992. La CIATha publicado datos similares para otros períodos en su serie de Boletines (Shímada, 1958; Alverson, 1959, 1960, 1963; Martin, 1962; Calkins y Chatwin, 1967, 1971; Calkins, 1975; Orange y Calkins, 1981) y en sus informes semales, trimestrales, y anuales. (PDF contains 102 pages.)

Fisheries management in the social domain: perspectives from Tanzania's Lake Victoria fishery

For a long time, the Tanzanian Fisheries Department has managed Tanzanian fisheries without incorporating other stakeholders within its management framework. On lake Victoria, the persistent use of illegal fishing gear and declining catches have led the government to realize that this system of fisheries management may no longer be viable, and have sought to incorporate fishing communities into the management structure. Through the creation of beach management units (BMUs), the Fisheries Departments have sought to persuade fishing communities to implement and enforce Tanzania's fishing regulations and to monitor the fishery. In this paper we explore a recently gathered data set that yields information on, amongst others, how Tanzanian fishing communities perceive the state of their resource base, how they view their relationship with the Fisheries Department, the efficacy of fishing regulations and other variables. We draw on a series of criteria developed by Ostron (1990) for institutional 'robustness' to explore various areas of institutional development on Lake Victoria, and to try and anticipate how the BMUs will fare. We argue there are many socio-political and economic factors that will determine how communities will receive and perceive their responsibilities towards government-imposed administrative structures at the local level, these will become 'socialized' such that they will vary from place to place. While this may bode well for problems of heterogeneity, it does not necessarily mean that fisheries management objective on Lake Victoria will be met

Regulation in Uganda's Lake Victoria fishery: historical and contemporary conditions

This paper sets out to explore how Uganda's lake Victoria fishery has been managed. It explores the management of the fishery during the protectorate period, and argues that the apparent success of regulation during this time may be attributed to the very heightened controls arising from Sleeping Sickness Controls. Once these were removed, entry into the fishery was rapid and uncontrolled, and the resultant impact on fish stocks was quickly felt. With its huge area, considerable shoreline, and innumerable islands, the lake Victoria fisheries service was quickly overwhelmed and disbanded as a result. In the early independence years, the Republic's government focused on developing the fishery, plans thwarted by turmoil of, and following, Idi Amin's reign. More recently, the fishery has prospered from Uganda's entry into the Nile perch fillet export market, which ahs adversely affected stocks. We present and comment on recently collected data that considers fishers' impressions of the status of the fishery, regulations and future managerial possibilities, and comment on these in the light of recent changes to Uganda's fisheries administration

Assessment of post-harvest losses in Nigeria fishery: the Kainji Lake model

The paper provides a description of a methodology used for quantitative assessment of post harvest losses in the Kainji Lake Fishery (Nigeria). The sample population was made up of 314 fisherfolk, 115 processors, 125 fish buyers and 111 fish sellers. For the determination of handling losses, 24,839 fishes weighing 2,389.31 kg belonging to 43 species were examined of which 10% by number and 9% by weight deteriorated at checking and 4% by number and 3% by weight at landing. Processing losses recorded 22% by number and 16% by weight deteriorated prior to and during smoking with the traditional 'Banda' kiln. During marketing, 16% of fish sold had deteriorated and 6% by weight of fish bought also deteriorated, mainly due to insect infestation during storage. Based on the 1995 yield estimate for Kainji Lake fishery, approximately 1000 tons of fish estimated at 80 million Naira were lost during handling alone. This figure would be much higher if the level of losses during processing and marketing are included. This assessment technique is recommended for use in obtaining quantifiable data on post harvest losses from other water bodies in Nigeria

Ecology and fishery in the Cross River Estuary - a research project

A literature review of 50 titles including nearly all relevant publications ensures adequate basis on the present level of knowledge. The proposal includes (a) the determination of the biozoenosis and selected environmental factors, and (b) of fishery and stock data of the main fish and shellfish species. The ecological research studies physical and chemical variables of the estuarine waters (flow velocity and direction, water temperature, conductivity, pH, dissolved oxygen, salinity, nutrients such as ammonium, nitrite, phosphate, silicate, pollutants such as hybrocarbons, pesticides and heavy metals, biochemical oxygen demand, chemical oxygen demand), plankton (bacterio-phyto-and zooplankton), benthos, sediment. The fishery biological and fishery investigations include: number of villages and fishermen, number of boats and gears by type, length and weight data of the main fishery objects with concentration on the shrimps, species and numbers of fish parasites. The ecological variables were monitored at fixed stations on sections in the Cross-River Estuary, Calabar and Great Kwara Rivers two times per month during spring and neap tides. The fishery biological and fishery variables were obtained during spring and neap tide too. For the determination of the detailed methodology the ecological and fishery part of the progeamme should be started with frame surveys based on a larger number of stations. These frame surveys should be repeated from time to time. Both parts of the programme are based on three years duration. It seems already appropriate to continue the work with selected representative stations, villages and variables in form of a long-term data chain

The status of the artisanal fishery of Lake Victoria, Kenya

Annual catches of fish in Lake Victoria, Kenya from 1976-1998 are assessed, catches from 5-15 boats selected randomly from targeted landing sites were recorded. Twenty three of the 256 Kenyan landing sites were covered by the survey. Selection of landing sites was not random but rather influenced by the presence of infrastructure and accomodation. Parameters recorded for each sampled fishing boat were: number of crew, gear type, size, time and duration of fishing. Catches were sorted into species and weighed

Stock assessment of Lates niloticus (L.), Oreochromis niloticus (L.) and Rastrineobola argentea (Pellegrin) using fishery dependent data from the Tanzanian waters of Lake Victoria

Catch data were collected from three beaches in the Mwanza area of lake Victoria, Tanzania for Oreochromis niloticus (L.), Rastrineobola argentea (Pellegrin) and Lates niloticus (L.). Sampling took place in October 1997 and February, June and September 1998. The CPUE for O. niloticus was 3.9 to 6kg boat super(-1) and for R. argentea from 98 to 282 kg boat super(-1). There was no obvious trend in catch rates for L. niloticus. The modal length for O. niloticus recorded at Chole beach was 34cm TL. In February, fish were larger (41-45 cm) than in the other surveys. Rastrineobola argentea caught in October 1997 had modal length at 65 mm TL with some smaller fish. In February and June prominent length modes occurred at 45 and 58 mm respectively, which may represent the same cohort as the small fish caught in October 1997. In September 1998, there were two length modes at 46 and 60 mm. The 60 mm fish may represent the same cohort seen in previous surveys, suggesting growth from approximately 30 mm to 60 mm in an eleven-month period. Lates niloticus landed at Kayenze beach over the four surveys had a modal length of 46 cm TL. Fish species encountered on the three beaches during the surveys were O. niloticus, R. argentea, Bagrus docmak Forsskall, Clarias gariepinus (Burchell), Protopterus aethiopicus Heckel, Labeo victorians Boulenger, Synodontis afrofischeri Hilgendorf, Synodontis victoriae Boulanger, Schilbe intermedius (L.), Brycinus jacksonii (Boulanger), Mormyrus kannume Forsskall and Haplochromine cichlids

WEFTA interlaboratory comparison on nitrogen determination by Kjeldahl digestion in fishery products and standard substances

14 Laboratorien aus 12 europäischen Ländern nahmen an einer Laborvergleichsuntersuchung zur Stickstoffbestimmung in Fischerzeugnissen und Standardsubstanzen nach Kjeldahl teil. 13 Laboratorien erzielten dabei Ergebnisse, die alle in engen Grenzen um die gefundenen Mittelwerte streuten. Der von den einzelnen Teilnehmern erzielte Variationskoeffizient war mit etwa 0,5 % gering. Auch die Standardsubstanzen mit bekanntem Stickstoffgehalt konnten überwiegend mit hinreichender Genauigkeit (98 % der vom Hertsteller angegebenen Gehalte) analysiert werden. Der ideale Kjeldahlaufschluß ist durch kurze Aufschlußzeiten (ca. 120 min), eine Aufschlußtemperatur bei 430° C und durch die Wahl des für die jeweilige Matrix geeigneten Katalysators gekennzeichnet.

Die deutsche Fischerei vor Nordnorwegen und bei der Bäreninsel im Dezember 1996 und im ersten Halbjahr 1997

Biological investigations were carried out onboard the German factory trawlers “Wiesbaden” and “Kiel” off the Norwegian coast and at Bear Island from December 1996 to June 1997. Data will be contributed to the assessments of the ICES “Arctic Fisheries Working Group”. Information on distribution and fishery of cod, haddock, saithe, redfish and Greenland halibut are given. Biological aspects of length- and age distributions, and stomach- and gonad investigations are represented. Some aspects of the function of sorting grids used in the Bear Island fishery are discussed.

Relation between TMAOase activity and content of formaldehyde in fillet minces and bellyflap minces from gadoid fishes

Minced fish is a significant component of a number of frozen fishery products like fish fingers, cakes and patties. Predominately minced fish is produced from gadoid species (Alaska pollack, cod, saithe, hake and others) possessing the enzyme trimethylamine oxide demethylase (TMAOase, E.C. 4.1.2.32) (Rehbein and Schreiber 1984). TMAOase catalyses the degradation of trimethylamine oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA), preferentially during frozen storage of products (Hultin 1992). In most gadoid species light muscle contains only low activity of TMAOase, the activity of red muscle and bellyflaps being somewhat higher. In contrast, the TMAOase activity in blood, kidney and other tissues, residues of which may contaminate minced fish flesh, may be higher for several orders of magnitude (Rehbein and Schreiber 1984).

Norwegens Fischerei 1996: Anlandungen und Erlöse weiter gestiegen

Norway’s sea fishery 1996 ranked 9th world wide. Preliminary data for 1996, as published in the Norwegean journal Fiskets Gang, show a further increase of the total catch by 114 000 tonnes, which now reached 2.63 million tonnes. The value of these landings were 8550 million nkr, up by 381 million nkr. The 5 most caught species were herring, cod, blue whiting and saithe. The 5 highest values, however, were obtained by cod, mackerel, herring, saithe and deepsea prawn. Considerable increases of prices were noted for jack mackerel (+142 %), mackerel (+133 %) and herring (+34 %).

Hinweise auf eine Überfischung grönländischer Grundfischbestände

At present, the severe decline of the fishery off Greenland is being discussed controversially. In contrast to overfishing, climate changes and emigration are itemized causal. Available German data on commercial catches and research cruises are presented for clarification. A few years after the beginning of heavy exploitation during the early sixties, the stocks of cod, golden and beaked redfish reflected a significant rejuvenescence based on catch analysis. Regular scientific surveys• for stock assessment purposes commenced in 1982 when the productivity of the stocks was already adversely affected due to low spawning stocks and extremely irregular recruitment. From this point of view, the results of the latest survey in 1995 showing stagnant fish biomass at record low level since 1991 are not surprising. The status of the cod stock is still considered severely depleted. Taking the high abundance of juvenile redfish into account, recovery of the groundfish stocks is unlikely in short term and depends on the non-predictable recruitment only.

The effect of long term exploitation by the gill net fishery on the multispecies fish stocks in Kainji Lake, Nigeria, 1969-1997

The findings are presented of an assessment made of the gillnet fishery in Kainji Lake, Nigeria from 1969 to the present, on the basis of data sets from commercial and experimental gillnet fishing, with the purpose to detect trends in some key fishery monitoring indicators. During this period, there has been an increase in the number of small meshed nets in the fishery resulting in a shift in the mode to lower mesh sizes; consequently, the average mesh size declined gradually in the fishery. This trend is found to be directly correlated with the decline in the CPUE and mean weight of the fish species. It is argued that the observed trend in CPUE and mean weight is forcing the fishermen to switch effort to gears such as traps which have very small meshes and can indescriminately take all sizes of the fish. It is shown that the catch composition by weight of Citharinus citharus, Lates niloticus and tilapias declined in the gillnet fishery in the late 70's and early 80's. Recent data, from 1994 to 1996, however indicates that C. citharus is recovering, but with declining mean weight. This suggests that the exploitation pattern is shifting to the smaller fish through the use of small meshed nets. In general, however, there has not been drastic changes in species bio-diversity in the Lake as a result of predatory effect and ecosystem overfishing as has happened in other great African Lakes. The species composition since lake formation continued to be dominated by fewer that 20 species. The potential yield for the lake has been estimated to be 32,166 tonnes (excluding clupeids) and the required optimum fishing effort to be 1,814 fishing canoes. In view of the relative stability of the species diversity in the lake and the current fish production level, it is proposed here that this MSY be adopted for all species. This would be achieved with the current effort level in the lake assuming that the efficiency of the fishermen and their gears do not improve. It should be reviewed after 10 or more years of catch and effort data collection. (PDF contains 65 pages)

The cast net fishery, Kainji Lake, Nigeria 1970-1997

This study was carried out to establish trends in the cast net fishery of Kainji Lake, Nigeria. The cast net fishery was second in importance to the gillnet fishery in the early years after impoundment of the lake and still continues to be an important component of the fishery. Some of the economically important species such as Citharinus spp, Tilapia spp, Labeo spp, Alestes spp and Synodontis spp are exploited by cast nets. The study has not revealed any drastic perturbation in the species diversity, catch composition, and any real ecosystem overfishing. On the other hand, both the catfish, Auchenoglanis spp and the predator Hydrocynus spp appear to have increased in the catch in recent years. Never-the-less there is a decline in the mean weight of the major exploited fish species due to the capture of under sized fishes without allowing them to grow to 'legally' marketable sizes. The use of small meshed cast net and also fishing in the shallow waters of the lake can give rise to this situation. Thus, there are signs of growth overfishing in the fish stocks. It must also be acknowledged that the situation is complicated by the fact that in a multi-gear fishery as on Kainji Lake, the cast net fishery could not be managed in isolation without due regard to the other competing gears. The catch per unit of effort (CPUE) has declined in the cast net fishery possibly due to the increase in effort by the major fishing gears over the years. The ongoing extension campaigns by the KLFPP appears to be having the desired effect, as there was reduction in the number of the major fishing gears on the Lake in 1997. It can be anticipated that if this trend continues, the CPUE will recover in the long run. Yields observed from the mesh selectivity study revealed that for major species in the cast net fishery, both by number and weight, were maximal at 2.5 inch mesh, which contrasts with the fact that current minimum allowable mesh in the Fisheries Edict for the Lake is 2.0 inch. The adoption of 2.5 inch as the minimum allowable mesh in the cast net fishery is recommended to be included in future revision of existing regulations. It is also recommended that for this control to have a desired effect, the casting of the net from the shore should be prohibited so as to reduce the incidence of juvenile mortality in the nursery areas. (PDF contains 28 pages)

Predictions of fish yields and the status of the Kainji Lake fishery, 1998

Length frequency data was collected for the 6 main species from the Kainji Lake fishery for up to 16 months. Growth parameters were estimated and used for virtual - population and length based cohort analysis. The results from cohort analysis suggest that before the ban on beach seines the maximum economic yield from the fishery was overshot by 70%. Yield per recruit analysis showed that the fish are caught far below their optimum size. Fishing gears and the timing responsible for this early mortality have been identified. After the eradication of seines from the lake a 10% increase in total catch revenue can be expected from the fishery. This is equivalent to an increase in income of Naira 18,300 per annum for each fishing entrepreneur using other methods. A scenario for the regulation of cast net mesh size together with the ban of beach seines has been presented. A further increase of Naira 142 million (N25,500 per entrepreneur) can be anticipated if this is implemented by the Kainji Lake Fisheries Management and Conservation Unit. It is expected that the annual increase in fishing effort presently experienced will cause future yields to decline. The rate of the decline has been reduced by the eradication of the beach seine fishery and will further fall if the minimum mesh size for cast nets is implemented. A recommendation is made to the Kainji Lake Fisheries Management and Conservation Unit to first consolidate the beach seine ban and then to implement a ban of undersized cast nets. (PDF contains 70 pages)