A Seven-year Study of the Fishery for Lake Whitefish, Coregonus clupeaformis, on Lake Winnipeg

1959 ◽  
Vol 16 (1) ◽  
pp. 107-120 ◽  
Author(s):  
L. C. Hewson
Keyword(s):  
Age Groups ◽  
Water Masses ◽  
Fishing Ground ◽  
Fishing Gear ◽  
Coregonus Clupeaformis ◽  
Inshore Water ◽  
Lake Winnipeg ◽  
Scale Reading ◽  
Temperature Changes ◽  
Average Size

A representative section of the Lake Winnipeg whitefish fishery was studied during seven summers. The average size of whitefish in samples numbering from 100 to 3,500 fish yearly varied with time and place, but trends were absent. Ages of whitefish in commercial catches, determined by scale reading, revealed three main age groups each year during six summers. Fishing success varied during 7 years and showed no indication of a trend toward better or worse fishing. Some parts of the fishing ground are but lightly exploited. Temperature changes in inshore water masses affected catches in some fishing gear.

A Study of Six Winter Seasons of Commercial Fishing on Lake Winnipeg, 1950–1955

1959 ◽  
Vol 16 (1) ◽  
pp. 131-145 ◽  
Author(s):  
L. C. Hewson
Keyword(s):  
Dissolved Oxygen ◽  
Age Groups ◽  
Annual Production ◽  
Average Weight ◽  
Commercial Fishing ◽  
Apparent Effect ◽  
Lake Winnipeg ◽  
Stizostedion Canadense ◽  
Average Size

Investigations of a Lake Winnipeg winter fishery for sauger, Stizostedion canadense, and yellow walleye, S. vitreum vitreum, during January and February each year revealed some significant changes in average size for two species as the season progressed, and from year to year. Average weight based on 50 to 1600 fish approximated 0.5 lb for sauger and 0.7 for walleye in most areas. Fishing success declined during the study period. A sample of the sauger catch revealed mainly age-groups III, IV and V. Fish catches appeared unrelated to either water temperatures or dissolved oxygen. Increased use of nylon nets had no apparent effect on annual production.

Changes in the Population of Lake Whitefish (Coregonus clupeaformis) in Lake Winnipeg from 1944 to 1969

1973 ◽  
Vol 30 (11) ◽  
pp. 1667-1682 ◽  
Author(s):  
E. B. Davidoff ◽  
R. W. Rybicki ◽  
K. H. Doan
Keyword(s):  
Age Groups ◽  
Total Dissolved Solids ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Coregonus Clupeaformis ◽  
Age Composition ◽  
Lake Winnipeg ◽  
Ecological Changes ◽  
Complete Collapse ◽  
Two Age Groups

Whitefish catches have fluctuated since 1952, and except in 1964 each successive peak has decreased in magnitude. Recently the overall trend has been a diminishing fishery with increasing effort.There has been a drastic change in age composition with time. Age-groups 5, 6, and 7 accounted for 81% of the catch from 1944 to 1948, age-groups 4, 5, and 6 for 89% from 1949 to 1955, age-groups 4 and 5 for 86% from 1959 to 1968, and age-groups 3 and 4 for 88% in 1969. The fishery is now dependent upon two age-groups instead of three. Natural failure of one or more important year-classes would result in a serious decline in catch, and partial or complete collapse of this fishery.Annual survival rate decreased from 34%, 1944–48 to 12%, 1959–69. Instantaneous natural mortality rate was estimated to be 0.72, and may be overestimated. The 1938–39, 1945–47, 1949, and 1957 year-classes were strong, while the 1940–44, and 1956, 1958, and 1961 year-classes were weak. The 1959 and 1960 year-classes appeared to be somewhat above average. Examination of data on total dissolved solids and temperature indicated that ecological changes were not responsible for the decline of whitefish in Lake Winnipeg.We judge that the optimum rate of fishing has been exceeded, and that the fishery itself is largely responsible for the depleted condition of the whitefish stocks in Lake Winnipeg. Fishing effort must be reduced to the point where the fishery is again dependent upon three year-classes. This should result in higher catches, and provide less fluctuation in annual catches.

Age and growth pattern of the thin-lipped mullet Liza Ramada in the Eastern coast of Libya.

2016 ◽  
Vol 5 (06) ◽  
pp. 4620
Author(s):  
Manal M. Khalifa ◽  
Ramadan A. S. Ali ◽  
Abdalla N. Elawad* ◽  
Mohammad El. ElMor
Keyword(s):  
Frequency Distribution ◽  
Age Groups ◽  
Age Determination ◽  
Age And Growth ◽  
Eastern Coast ◽  
Growth Equation ◽  
Length Frequency Distribution ◽  
Length Frequency ◽  
Scale Reading ◽  
Von Bertalanffy Growth Equation

Age and growth characteristics of the thin-lipped Grey Mullet (Liza ramada) were investigated in Eastern coast of Libya. Aging was done by two methods: counting annuli on scales and by length frequency distribution, a total of 218 scales were studied for age determination, in addition of 334 fishes specimen for length frequency distribution reading. Four age groups were determined from scale reading, and five age groups from length frequency distribution methods, the parameters of the Von Bertalanffy growth equation for both sex of all individuals were estimated at 35.4 cm, 0.187 per year, -1.14 years and 2.4, for male were estimated at 35.7 cm, 0.17 per year, -1.367 and 2.3, for female were 38.6 cm, 0.156 per year, -1.383 and 2.4, for L∞, k and t0, and φ′, respectively.

scholarly journals Harmonization of laws related to the protection of artisanal fishermen fishing grounds in Aceh Province

2021 ◽  
Vol 869 (1) ◽  
pp. 012054
Author(s):  
S Sulaiman ◽  
M A Abdullah ◽  
T M Mansur ◽  
N Roesa
Keyword(s):  
Coastal Waters ◽  
Important Task ◽  
Fishing Ground ◽  
Small Scale ◽  
Fishing Gear ◽  
Potential Conflict ◽  
Legal Documents ◽  
Aceh Province ◽  
The Government ◽  
Harmonization Of Law

Abstract This paper aims to examine how to protect of artisanal fishermen fishing ground and the policies that protect them. Small-scale fisher fishing grounds has to have a special attention due to their limitation. They are using very simple fishing gear, so they can’t sail far away from the coastal waters. The Fishing law give a specific attention for this matter, by limiting fishermen with 5 gross tonnage (GT) are only able to conduct their activities within the coastal waters. This study combines legal documents and the results of interviews with fishermen on 5 GT vessel. this studi of find, then the Law Number 27/2016 changed this regulation by increasing gross tonnage for small-scale fishermen from 5 became 10 GT, and it attract more serious problems for these small-scale fishermen since they have no exclusive fishing ground anymore. It will also affect to changes of fishing lane; fishing ground and vessels authorization procedure. By increasing GT, the 10 GT vessels also have rights to sail in the same fishing ground with 5 GT vessels and it’s created a potential conflict between the fishermen. So, harmonization of law is important task for the government in avoiding the overlapping rules on vessels criteria, by choosing law that prioritize on small-scale GT vessels.

A STUDY OF THE MAY FLIES (HEXAGENIA) OF LAKE WINNIPEG

1932 ◽  
Vol 7 (1) ◽  
pp. 177-201 ◽  
Author(s):  
FERRIS NEAVE
Keyword(s):  
Economic Status ◽  
Maximum Growth ◽  
Economic Importance ◽  
Coregonus Clupeaformis ◽  
Large Area ◽  
Lake Winnipeg ◽  
The North ◽  
Different Seasons ◽  
North Part ◽  
Males And Females

The economic status of the May flies (Hexagenia) of lake Winnipeg is discussed. The nymphs are particularly important as food for sturgeon (Acipenser fulvescens), whitefish (Coregonus clupeaformis), light-backed cisco or tullibee (Leucichthys zenithicus), goldeye (Hiodon chrysopsis), and sauger (Lucioperca canadense). Two species are present in abundance, H. limbata occulta and H. rigida, but the former outnumbers the latter by a ratio of 7 to 1. Characters are given for the separation of all stages of these species and their habits are described. Eggs of occulta were hatched after artificial insemination. Later development of both species was followed by statistical measurements of nymphs secured at different seasons. The life cycle extends over two years. Sizes at which moults take place are indicated. Maximum growth is in August and is correlated with the amount of phytoplankton in the lake. No growth takes place in winter. The number of nymphs of occulta of 10 mm. and more is estimated at 62,000,000 per sq. kilometre in the southern part of the lake, and 93,000,000 in the neighbourhood of the Narrows. Corresponding estimates for rigida are 4,500,000 and 44,000,000. Both species are scarce or absent over a large area in the north part of the lake. H. occulta shows a 10 per cent, preponderance of females but is probably not parthenogenetic. Males and females of rigida occur in equal numbers. Parasites are noted, but are local in distribution. Occulta is of greater economic importance than is indicated by the numerical ratio between the two species.

Differences in predicted catch composition between two widely used catch equation formulations

2009 ◽  
Vol 66 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Trevor A. Branch
Keyword(s):  
Age Groups ◽  
Correct Choice ◽  
Fishing Gear ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Gear Selectivity ◽  
Different Types ◽  
Catch Composition ◽  
Continuous Formulation ◽  
Discrete Formulation

Fishing gear selectivity varies among different types of fish (e.g., species, age, sex, or length groups), but their relative catch composition also depends on the fishing process. The continuous (Baranov) formulation assumes that fishing mortality and natural mortality occur together during the fishing season and that there are multiple encounters between fish and fishing gear. For this formulation, predicted catch composition depends on fishing mortality, and at high fishing mortality levels the entire population can be caught provided the selectivity is nonzero for all age groups. In contrast, the discrete formulation assumes that fishing mortality occurs separately from natural mortality and that fish encounter at most only one set of fishing gear. The discrete formulation is easier to compute, but the predicted catch composition is independent of fishing mortality, and some of the population remains unexploitable. The correct choice of equations depends on the particular fishery and fishing mortality levels; at low fishing mortality levels the predictions differ little, but at high fishing mortality levels where multiple gear encounters could occur, the continuous formulation is preferable.

Subpopulation Status of Lake Whitefish (Coregonus clupeaformis) in Lake Winnipeg

1990 ◽  
Vol 47 (8) ◽  
pp. 1484-1494 ◽  
Author(s):  
A. H. Kristofferson ◽  
J. W. Clayton
Keyword(s):  
Lactate Dehydrogenase ◽  
Coregonus Clupeaformis ◽  
Genetic Contribution ◽  
Lake Whitefish ◽  
Morphometric Measurements ◽  
Lake Winnipeg ◽  
Meristic Counts ◽  
Grand Rapids ◽  
Parent Stock ◽  
Glycerol 3 Phosphate Dehydrogenase

Spawning lake whitefish in Lake Winnipeg from Dauphin River–Lake St. Martin, Traverse Bay, Berens River–Poplar River–Big Black River and Grand Rapids and in Little Playgreen Lake are accorded subpopulation status based on morphometric measurements, meristic counts, and differences in frequencies of alleles at the muscle glycerol-3-phosphate dehydrogenase (g-3-pdh-b) locus. The frequency of the g-3-pdh-b-3 allele in samples from Dauphin River–Lake St. Martin was 0.77 compared with 0.46 for whitefish from the remainder of Lake Winnipeg and Little Playgreen Lake. Two loci for isocitrate dehydrogenase and one lactate dehydrogenase locus are also polymorphic in these fish but no significant allele frequency differences were found at these loci among the samples of spawners compared above. Hatchery-reared lake whitefish, obtained from stock in Clearwater Lake and William Lake and planted as fry or eyed eggs in Lake Winnipeg at Dauphin River and Grand Rapids, do not appear to have made a detectable genetic contribution to the local whitefish stocks, based on differences in g-3-pdh-b and idh Bβ allele frequencies among parent stock and spawners captured near the release sites.

Seasonal variations in the Indian Ocean along 110°E. I. Hydrological structure of the upper 500 m

1969 ◽  
Vol 20 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
Surface Waters ◽  
Water Masses ◽  
Surface Currents ◽  
Temperature Changes ◽  
East Indian ◽  
Hydrological Structure ◽  
The Indian Ocean ◽  
The Tropics ◽  
East Indian Ocean

Tropical and subtropical water masses at surface and subsurface depths were separated by their salinity, temperature, oxygen, and nutrient characteristics. The annual mean depths and latitudinal extent of these water masses were determined. Annual changes in the upper 50 m were generally so small relative to those found in other oceans that advection and mixing must have been less important in their genesis than local climatic changes. There was a barely significant seasonal rhythm in surface phosphate and nitrate, with peak occurrences of each some 6 months apart. At each latitude the permanent thermal discontinuity centred around a particular isotherm varied little in intensity during the year, but rose and fell in accordance with surface currents. The thermocline south of c. 18�S. varied little in depth but greatly in intensity during the summer. The depth of the mixed layer was much less in summer and at all times shallower in the tropics. The depth of this layer was governed more by the accumulation of surface waters by zonal currents and eddies, than by wind stress or convective overturn. Therefore there was little difference from south to north, or month to month, in average nutrient values of this mixed column. The movement of the various surface waters, deduced from salinity and temperature changes during the year, usually agrees with geostrophic currents across 110�E, and ships' observations of surface currents in the south-east Indian Ocean.

The New South Wales Tiger Flathead Neoplatycephalus macrodon (Ogilby). II. The Age Compositon of the Commercial Catch, Overfishing of the Stocks, and Suggested Conservation

1952 ◽  
Vol 3 (1) ◽  
pp. 1 ◽  
Author(s):  
WS Fairbridge
Keyword(s):  
New South ◽  
Age Groups ◽  
Fishing Ground ◽  
Alternative Measure ◽  
Age Group ◽  
Catch Per Unit Effort ◽  
Commercial Catch ◽  
Conservation Measure ◽  
South Wales ◽  
Post War

The commercial flathead catch is analysed into its component age-groups. The results are expressed in numbers and weight of each age-group caught in each month. The results indicate an absence of natural fluctuations in abundance of the year-groups during the series of years covered. The post-war decline in the catch of flathead is discussed in the light of this analysis. The catch has fallen from 5,700,000 lb. in 1944–45 to 2,100,000 lb. in 1948–49. The catch of flathead for a period between the wars is estimated at over 10,000,000 lb. per year. The stock of flathead has thus shown a failure to recover during the war-time rest, as well as a sudden fall with the inception of heavy fishing of recent years. Possible reasons for these changes in the flathead stock are discussed. It is suggested that the numbers of recruits are limited by the numbers of spawning adults. The results obtained from this work are fuller, but in entire agreement with those of the earlier paper on the trawlfishery as a xvliole. The adoption of conservation measures is urged. The trawlfishery is now dependent on two hitherto discarded species of poorer quality than the flathead, and the better of these is already showing a reduced catch per unit effort of fishing. The most important conservation measure is that suggested in the earlier paper — a reduction of the fleet to the equivalent of 13 trawlers. It is regarded as probable that if this step is not taken, the annual trawlfish catch will continue to decline. Closure of the Botany fishing ground is suggested as a further, but not an alternative, measure.

scholarly journals PERIKANAN TUNA SIRIP KUNING (Thunnus albacares Bonnaterre, 1788) PADA ARMADA TONDA DI SAMUDERA HINDIA SELATAN JAWA

2019 ◽  
Vol 11 (3) ◽  
pp. 161
Author(s):  
Maya Agustina ◽  
Bram Setyadji ◽  
Prawira Atmaja Rintar Pandapotan Tampubolon
Keyword(s):  
Indian Ocean ◽  
Size Structure ◽  
Landing Site ◽  
Yellowfin Tuna ◽  
Fishing Gear ◽  
Thunnus Albacares ◽  
Skipjack Tuna ◽  
The Indian Ocean ◽  
Average Size ◽  
Relationship Of

Tuna sirip kuning (Thunnus albacares) merupakan hasil tangkapan terbanyak dibandingkan dengan jenis tuna lainnya di Indonesia. Ketersediaan stok tuna sirip kuning di Samudra Hindia, pada saat ini, diperkirakan dalam keadaan lebih tangkap. Oleh karena itu, pengelolaan secara tepat dan bertanggungjawab penting dilakukan untuk melindungi spesies tuna, salah satu caranya dengan mengkaji alat tangkap yang digunakan. Tulisan ini bertujuan untuk mengungkapkan produktivitas dan hasil tangkapan armada tonda, serta struktur ukuran dan hubungan panjang bobot ikan tuna sirip kuning yang di daratkan di selatan Jawa. Komposisi tangkapan tertinggi dari armada tonda diseluruh pendaratan ikan tuna di selatan Jawa terdiri atas tuna sirip kuning dan cakalang. Analisis CPUE menunjukkan hasil yang fluktuatif di setiap lokasi pendaratan tuna sirip kuning di Selatan Jawa. Tuna sirip kuning yang tertangkap di selatan Jawa dengan armada tonda sebagian besar adalah ikan yang belum layak tangkap karena berukuran kurang dari 100 cmFL. Struktur ukuran panjang tuna sirip kuning yang tertangkap semakin ke Timur semakin panjang ukurannya. Pola pertumbuhan tuna sirip kuning yang tertangkap di Binuangeun memiliki pola isometrik, PPN Palabuhanratu bersifat allometrik Positif, PPP Sadeng, P2SKP Pacitan, PPN Prigi dan P2SKP Sendang Biru bersifat allometrik negatif. Yellowfin tuna (Thunnus albacares) is the largest catch compared to other tuna species in Indonesia. The availability of yellowfin tuna stock in the Indian Ocean, at present, is estimated to be in overfished condition. Therefore, proper and responsible management is important to protect the species. One of the ways is by studying the used fishing gear. This paper aims at determining vessel’s productivity, as well as composition, size structure and length-weight relationship of yellowfin tuna catches from troll line fleet in the Indian Ocean part of south Java. The highest catch of tuna in all of the troll line landing places was yellowfin tuna, following by skipjack tuna. CPUE analysis showed fluctuating results at each landing site. Yellowfin tuna sizes caught by troll line fleet were mostly less than 100 cmFL and categorized as should not be properly caught. Geographically, getting to the east the average size of the catches tend to be larger. The growth pattern of yellowfin tuna catches landed in Binuangeun was isometric; Palabuhanratu was positive allometric; while those landed in Sadeng, Pacitan, Prigi and Sendang Biru were negative allometric.

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