Index numbers and productivity measurement in multispecies fisheries: an application to the Pacific Coast Trawl Fleet

This study is concerned with the measurement of total factor prodnctivity in the marine fishing industries in general and in the Pacific coast trawl fishery in particular. The study is divided into two parts. Part I contains suitable empirical and introductory theoretical material for the examination of productivity in the Pacific coast trawl Deet. It is self-contained, and contains the basic formulae, empirical results, and discussion. Because the economic theory of index numbers and productivity is constantly evolving and is widely scattered throughout the economics literature, Part D draws together the theoretical literature into one place to allow ready access for readers interested in more details. The major methodological focus of the study is upon the type of economic index number that is most appropriate for use by economists with the National Marine Fisheries Service. This study recommends that the following types of economic index numbers be used: chain rather than fIxed base; bilateral rather than multilateral; one of the class of superlative indices, such as the Tornqvist or Fisher Ideal. (PDF file contains 40 pages.)

Survey of fish protective facilities at water withdrawal sites on the Snake and Columbia Rivers

Proliferation of water withdrawals and new pump intake and screen designs has occurred with the growth of irrigated agriculture along the Columbia and Snake Rivers. Concern for the protection of anadromous and resident fish populations resulted in formulation of a survey of the water withdrawal systems. The survey included distribution studies of juvenile fish near pump sites and field inspection of those sites to determine adequacy of screening for protection of fish. A total of 225 sites were inspected in 1979 and 1980, with a follow-up inspection of 95 sites in 1982. Results indicated a definite trend toward lack of concern for the condition of fish protective facilities. Only 4 out of 22 sites not meeting criteria in 1979 had been upgraded to acceptable conditions. Of more concern, 13 of the sites meeting criteria in 1979 were below criteria when reinspected in 1982. Some of the discrepancies included lack of protective screens, poorly maintained screens, and screens permitting excessive velocity that could result in impingement of larvae or small fish. A conclusion from these surveys is that if adequate protection for fish is to exist, screens for water withdrawals need to be properly installed, inspected, and maintained. (PDF file contains 40 pages.)

Ichthyoplankton survey of the estuarine and inshore waters of the Florida Everglades, May 1971 to February 1972

Quarterly ichthyoplankton sampling was conducted at 16 estuarine and 24 inshore stations along the Florida Everglades from May 1971 to February 1972. The area is one of the most pristine along lhe Florida coast. The survey provided the first comprehensive information on seasonal occurrence, abundance (under 10 m' of surface area), and distribution of fish eggs and larvae in this area. A total of 209,462 fish eggs and 78,865 larvae was collected. Eggs were identified only as fish eggs, but among the larvae, 37 families, 47 genera, and 37 species were identified. Abundance of eggs and larvae, and diversity of larvae, were greatest in the inshore zone. The 10 most abundant fish families which together made up 90.7% of all larvae from the study area were, in descending order of abundance: Clupeidae, Engraulidae, Gobiidae, Sciaenidae, Carangidae, Pomadasyidae, Cynoglossidae, Gerreidae, Triglidae, and Soleidae. Clupeidae, Engraulidae, and Gobiidae made up 59.9% of all larvae. The inshore zone (to a depth of about 10 m) was a spawning ground and nursery for many fishes important to fisheries. The catch of small larvae (<>3.5 mm SL) indicated that most fishes identified from the 10 most abundant families spawned throughout the inshore zone at depths of <> 10 m, but Orthopristis chrysoptera, Gerreidae, and Prionotus spp. spawned at depths > 10 m, with offshore to inshore (eastward) larval transport. Salinity was one of several environmental factors that probably limited the numbers of eggs and larvae in the estuarine zone. Abundance of eggs and larvae at inshore stations was usually as great as, and sometimes greater than, the abundance of eggs and larvae at offshore stations (due west of the Everglades). (PDF file contains 81 pages.)

Survey of El Nino 1957-58 in its relation to tropical pacific meteorology

ENGLISH: The survey aims at demonstrating the close relationship between anomalies of sea temperature observed along the tropical Pacific coast of the Americas and those observed in the oceanwide tropical belt. The survey also covers the variations, from 1952 to the present, of the trade-wind circulations which prove to be responsible for the major part of the anomalies in sea surface temperature. Finally, the thermal feedback effects of the oceanic anomalies upon the large-scale circulation of the atmosphere are treated in a preliminary fashion. SPANISH: El estudio trata de demostrar la estrecha relación que existe entre las anomalías observadas de la temperatura del mar a lo largo de la costa tropical de las Américas y las observadas en la faja tropical de todo el océano. El estudio incluye también las variaciones, desde 1952 hasta el presente, de la circulación de los vientos alisios que demuestra ser responsable por la mayor parte de las anomalías de temperatura de la superficie del mar. Finalmente los efectos termales de las anomalías oceánicas sobre la circulación en gran escala de la atmósfera son tratados en forma preliminar. (PDF contains 62 pages.)

Maifische an der deutschen Nordseeküste - zum Auftreten von Finte (Alosa fallax) und Alse (Alosa alosa)

Quantitative data on twaite shad are collected annually in spring and autumn since 1974 by the Demersal Young Fish Survey. Results for occurrence of these anadromous species show that twaite shad has been caught in the entire Wadden Sea area despite of the poorly suited 3-m shrimp beam trawl applied in the survey. Regional differences occur: Only sporadic catches are observed in the northern part of the German Wadden Sea, while more frequent ones occurred southwards and in the East Frisian Islands region. The obvious recent increase of abundance of Alosa fallax in spring allows for a lower ranking in the Red List of Endangered Species, while Allis shad (Alosa alosa) requires the same classification, as it was the never caught during the thirty years of surveys.

Warum Fischereiwissenschaftler nicht mit kommerziellen Netzen fischen

“Wrong trawl, wrong rigging – that’s why research ship cannot find cod” – in a polemic article in the April number of “Fishing News International” British fishermen accuse fishery scientists of using the wrong trawl for their bottom trawl surveys in the North Sea. They wrote the GOV is unsuited to catch cod and therefore the cod stock could be in a much better shape than assessed by the scientists. In this paper the characteristics of a scientific survey trawl and the results of comparison fishing experiments are listed.

Einfluss des Tag-Nacht-Verhaltens von Fischen auf das Ergebnis hydroakustischer Messungen

Echo integration is an established method for stock estimation. However, this method is not free of errors like every other measuring method. Especially the variation between day and night behaviour of fish may lead to large measuring errors. A new method is represented detecting such systematic errors, exemplified by investigations during the international hydroacoustic survey on the spring spawning herring in the Norwegian Sea. For this method all measured sA-values are sorted by starting time of the measuring unit distance. In order to reduce random influences a moving average over five time intervals is computed. When displaying these values in a diagram makes it is very easy to detect systematic errors based on the differences in day-night behaviour. For both species, herring and blue whiting, stock estimations are calculated based on the measured sA-values and the results of the analysed trawl catches. The influence of the differnt day and night behaviour of herring on the results of its biomass estimation is rather low. For blue whiting the measured values were about three time higher during day time than during night time. The result of this investigation should initiate a change of the evaluation procedure for stock estimation based on hydroacoustic measurements.

Survey on the status of Computational Design research and practice

This report presents the results from a survey of current practice in the use of design optimization conducted amongst UK companies. The survey was completed by the Design Optimization Group in the Department of Engineering at Cambridge University. The general aims of this research were to understand the current status of design optimization research and practice and to identify ways in which the use of design optimization methods and tools could be improved.

A summary of the inventory survey of Nigeria inland waters and preliminary estimates of their fish yield potentials

A summary of the inventory survey of Nigeria inland waters is presented. The survey reveals that Kano State tops the list in reservoir development with an existing water surface area of about 42,773 ha, while Anambra State has the least with about 38 hectares. No reservoir was recorded for Lagos and Rivers States. However, in aspects of existing fish ponds, a total of about 471 ha was recorded for Plateau State and about 5 ha for Niger State. Preliminary estimates of Nigeria's fish yield potentials based on established production records of comparable water bodies in the tropics, at different levels of management, show that the available water mass in the country, estimated at about 12.5 million hectares, could yield a minimum of about 334,214 metric tonnes (m.t.) of fish per annum with little or no management and a maximum of about 511,703 metric tonnes per annum with adequate management. Comparison of the potential yields from inland sources with the projected fish production in Nigeria (1981-1985) based on supply and demand statistics shows that potential yield from inland sources even at a low level of management is relatively higher than the projected inland production and more than double the observed production. The variation between the potential and the observed fish yields in the country has been attributed to the absolute lack of management strategies for our various inland waters. The paper elaborates on possible management strategies for various categories of inland waters as a prelude towards increased fish production in the country

Market survey of the periwinkle Tympanotonus fuscatus in Rivers State: Sizes, prices, trade routes and exploitation levels

Tympanotonus fuscatus was collected from 23 markets through Rivers State (Nigeria), a few in neighbouring states, and from an unexploited population at Buguma. The size distribution of shells was determined,and information on prices and trade routes was also obtained. The mean shell length of specimens from the unexploited Buguma population was 46.4 mm, compared to 30.4 mm for the Buguma market samples. Mean sizes in other markets showed a geographic pattern: the smallest were from the Adoni-Ogoni-Opobo sector (28.1-30.9); the largest were from the Nembe-Brass sector (37.7-44.2) and Bendel State (35.7-45.6); The results suggest the population structure of Tympanotonus in much of Rivers State has been strongly impacted by overharvesting. They show that local market as well as some in Cross River State, are increasingly being supplied by road with specimens from the Benin River area of Bendel State. Differences between shell types; and relations between shell size, selling price and market distance from source, are also discussed

Culturable fish seeds in Nigerian waters: A research survey (1978-1985)

The desired species identified in this survey include mullets, catfishes, fast growing fish predators, species for control of weeds and grass it, ponds, cichlids and shrimps. Five coastal states: Lagos, Ondo, Bendel, Rivers, and Cross River were covered in the studies. Investigations were also carried into the major rivers and their tributaries. A combination of the estimation methods of Le Cren, (1962) and Pitcher and Mac Donald (1973) was employed in the analysis of data. From the detailed data collected from (1978-1985), the survey indicated that about 100 million fish seeds can be collected annually from Nigerian waters using appropriate gear-seine nets, cast nets, and fish traps. Of this number, 60% is available along the coastal belt of the country while 40% is in the major rivers, their tributaries and swamps. At the present level of fish culture development in Nigeria, this is more than enough, even after allowing for 50% mortality due to handling and transportation stress

A preliminary survey of the helminth fish parasites in Imo River

A preliminary survey of the helminth fish parasites was carried out in Imo River (Nigeria). A total of 191 fishes belonging to 15 genera were examined and only 13.6% were infested with various species of helminth parasites which is low percentage of infection. The following helminth parasites were recorded. Wenyonia virilis, kainji; Wenyonia sp., Procamallanus laeviconchus; Procamallanus sp., Sprionoura congolense; Spironoura sp., Cucullanus sp. and Serradacnitis serrata. It was found that helminth parasites showed some degree of specificity in their distribution within their fish hosts. This specificity could be as a result of the physiochemical and physiological factors operating in the gut such as pH, osmotic tension, oxygen tension and nutrient levels. The results also revealed that age and sex influence helminth parasites infections in fishes

Preliminary survey of parasites of Clarias in the Niger Delta area of Nigeria

A total of 160 Clarias lazera were collected with line hood between April and June 1984 from the Niger Delta area and observed for the presence of parasites. The results revealed the presence of three classes of endo-parasites: Trematodes (47%), nematodes (46%) and cestodes (7%). It was found that, the parasites have great affinity for the spleen (34%) and the liver (28.3%). Also, smaller fish habored more parasites than large fish. Though the investigation is still continuing, the study reveals the presence of parasites in Clarias and calls for measures to prevent wide-spread infestation in fish ponds and suggests treatment of infested fish

Data collected on tuna spawning survey cruise July 1-20, 1957: data report

Studies of gonads of yellowfin and skipjack tunas (Neothunnus macropterus and Katsuwonus pelamis) carried out by the Inter-American Tropical Tuna Commission indicate that during summer months the offshore area in the region of the Revilla Gigedo Islands is a spawning location for these two species (Schaefer and Orange, 1956). In July of 1957 a cruise "Tuna Spawning Survey" was made aboard the vessel ORCA to make plankton hauls and to collect ancillary data for the primary purpose of surveying abundance of tuna larvae in this region. (PDF contains 17 pages.)