Planting Sea Trout Ova 1952

Three men planting out Sea trout ova in a beck in North West England, UK, in 1952. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

Maryland commercial fisheries statistics, 1951-1952

This bulletin is the third of a series begun in 1948, presenting detailed data on the commercial fin-fishery of Maryland. A full description of the techniques of collection and tabulation were included in the first bulletin [Publication 69], and inasmuch as identical procedures have been employed throughout the program, further mention of methods is not made. As in past years, records were received on a voluntary basis from approximately 94% of all licensed fishermen. Most of the records were submitted in the form of weekly or monthly summaries. The statistics set forth were derived from records obtained only from licensed commercial fishermen and contain no data pertaining to small unlicensed units of fishing gear, or to the sport fishery.

An approach to estimating rockfish biomass based on larval production, with application to Sebastes jordani

An assessment of the total biomass of shortbelly rockfish (Sebastes jordani) off the central California coast is presented that is based on a spatially extensive but temporally restricted ichthyoplankton survey conducted during the 1991 spawning season. Contemporaneous samples of adults were obtained by trawl sampling in the study region. Daily larval production (7.56 × 1010 larvae/d) and the larval mortality rate (Z=0.11/d) during the cruise were estimated from a larval “catch curve,” wherein the logarithm of total age-specific larval abundance was regressed against larval age. For this analysis, larval age compositions at each of the 150 sample sites were determined by examination of otolith microstructure from subsampled larvae (n=2203), which were weighted by the polygonal Sette-Ahlstrom area surrounding each station. Female population weight-specific fecundity was estimated through a life table analysis that incorporated sex-specific differences in adult growth rate, female maturity, fecundity, and natural mortality (M). The resulting statistic (102.17 larvae/g) was insensitive to errors in estimating M and to the pattern of recruitment. Together, the two analyses indicated that a total biomass equal to 1366 metric tons (t)/d of age-1+ shortbelly rockfish (sexes combined) was needed to account for the observed level of spawning output during the cruise. Given the long-term seasonal distribution of spawning activity in the study area, as elucidated from a retrospective examination of California Cooperative Oceanic Fisheries Investigation (CalCOFI) ichthyoplankton samples from 1952 to 1984, the “daily” total biomass was expanded to an annual total of 67,392 t. An attempt to account for all sources of error in the derivation of this estimate was made by application of the delta-method, which yielded a coefficient of variation of 19%. The relatively high precision of this larval production method, and the rapidity with which an absolute biomass estimate can be obtained, establishes that, for some species of rockfish (Sebastes spp.), it is an attractive alternative to traditional age-structured stock assessments.

East African Fisheries Research Organization Annual Report 1952

Several important advances have been made in our knowledge both regarding the factors which determine fertility in tropical lakes and the fish that live in them. As a result of our investigations a new theory has been put forward regarding the part played by animals in the bionomics of a lake; this theory, stated somewhat baldly, is that within certain limits the greater the number of animals in a shallow tropical lake, the greater becomes its potential fertility, and therefore the greater the number of animals it can support. The theory arises as a logical conclusion, once we accept the fact that the rate of production in such a lake is determined by the rate at which organic matter is decomposed. Bottom deposits which consist mainly of vegetable matter decompose slowly, whereas deposits which contain a high proportion of matter of animal origin decompose more rapidly. Thus the more animals in a lake, particularly animals which feed on plant material, the faster the biological cycle can proceed and the greater the density of animals it can support. This new concept will have a very profound influence on our ideas concerning the consequences of overfishing tropical waters. It also shows that efforts must be made to encourage and protect all herbivorous and detritus feeding animals, whether they be copepods, fish, or hippopotami, and whether they are of immediate economic importance or not.

Annual Report of the Game and Fisheries Department for the year ended 31st December 1952

The annual report presents information on Lake Victoria, Lake Albert (including tbe Albert Nile and associated Fisheries)-Report by Lake Albert Fisheries Officer,Lake Kyoga and Waters of Eastern Uganda-Report by Fisheries Officer, Serere. Lakes George, Edward and Waters of Western Uganda -Report by the Fisheries Officer, Kichwamba Fish Farming-Report by the Fisheries Officer, Fish Fanning,dams,crocodiles. It presents information on angaling, Trouting, Nile Perch and Ripon Falls Barbel

Filariasis research annual report 1952

This 1952 report gives details of findings in the Southern and Southern Highlands Provinces. Accordingly in this publication a return is made to the more usual method of presentation, a summary being given of work done, with detailed sectional reports.