Use of length-based models to estimate biological parameters and conduct yield analyses for male Dungeness crab (Cancer magister)

2004 ◽  
Vol 61 (11) ◽  
pp. 2126-2134 ◽  
Author(s):  
Z Zhang ◽  
W Hajas ◽  
A Phillips ◽  
J A Boutillier
Keyword(s):  
Carapace Width ◽  
Natural Mortality ◽  
Biological Parameters ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Model Yield ◽  
Exploitation Rate ◽  
Threshold Ratio ◽  
Yield Per Recruit

Length-based models were developed for the male Dungeness crab (Cancer magister) population on the Fraser delta near Vancouver, British Columbia. The models incorporate the probability of moulting, moult increments, natural mortality during moulting and non-moulting periods, direct fishing mortality, and handling mortality that occurs when sublegal-sized crabs are caught and released. The models were used to investigate how long-term yield might be affected by the combination of handling mortality and an intensive fishery. The models were calibrated to survey data, and key biological parameters were estimated. The probability of moulting is near one for male crabs in the 130- to 150-mm carapace width range and decreases as crabs get larger. There is a 70.1% probability a crab will survive the 1-month period beginning with a moult. The non-moulting natural mortality rate is 0.97 year–1. When handling mortality is incorporated into the model, yield per recruit increases with the exploitation rate until it reaches approximately 94%. F0.1 is equivalent to 70%. An approach was developed to calculate the threshold ratio of discarded to retained crabs beyond which fishing would reduce the long-term yield.

scholarly journals DINAMIKA POPULASI DAN TINGKAT PEMANFAATAN RAJUNGAN (Portunus pelagicus Linnaeus,1758) DI PERAIRAN TELUK JAKARTA

2018 ◽  
Vol 1 (1) ◽  
pp. 73
Author(s):  
Anthony Sisco Panggabean ◽  
Andina Ramadhani Putri Pane ◽  
Ap’idatul Hasanah
Keyword(s):  
Carapace Width ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Portunus Pelagicus ◽  
Relationship Analysis ◽  
Marine Crustaceans ◽  
Exploitation Rate ◽  
Main Target ◽  
First Maturity

Rajungan (Portunus pelagicus) merupakan salah satu jenis krustasea laut yang bernilai ekonomis penting yang menjadi target utama tangkapan di perairan Teluk Jakarta. Penelitian ini bertujuan untuk mengkaji dinamika populasi rajungan yang berguna sebagai dasar pengelolaannya. Penelitian dilakukan pada periode Januari sampai dengan November 2015. Hasil penelitian menunjukkan bahwa hubungan panjang berat rajungan bersifat allometrik positif dan rata-rata ukuran pertama kali matang gonad (Lm) sebesar 106,81 mm (lebar karapas), laju pertumbuhan (K) sebesar 1,0 per tahun dan lebar karapas infinitif (CW)  sebesar 157 mm. Laju kematian akibat penangkapan (F) sebesar 1,12 per tahun dan laju mortalitas alami (M) sebesar 1,14 per tahun. Laju eksploitasi (E) sudah berada pada tahapan penuh atau fully exploited, dengan demikian perlu adanya pengendalian upaya penangkapan.Blue swimming crabs (Portunus pelagicus) is one of the important marine crustaceans species forming the main target of fishing in the Jakarta Bay. This study aims to assess the population dynamics of crab for the basis e for their management. The study was conducted from January to November 2015. The result showed that carapace width and weigth relationship analysis was isometric and the estimated length at first maturity (Lm) was 106.81 mm (in carapace width), growth rate (K) was 1 mm per year, carapace width infinit (CW) was 157 mm, fishing mortality (F) was 1.12 per year and natural mortality rate (M) at about 1.14 per year. The exploitation rate (E) was predicted at fully exploited level, so that control of fishing effort are needed.

Estimated Preseason Abundance in the California Dungeness Crab (Cancer magister) Fisheries

1982 ◽  
Vol 39 (8) ◽  
pp. 1077-1083 ◽  
Author(s):  
Richard D. Methot Jr. ◽  
Louis W. Botsford
Keyword(s):  
Large Fraction ◽  
Northern California ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Common Assumption ◽  
Central California ◽  
Large Size ◽  
Exploitation Rate ◽  
The Common ◽  
High Catch

Annual preseason abundance for the central and northern California Dungeness crab (Cancer magister) fisheries is estimated from the decline in catch per unit of effort (CPUE) within each fishing season. The results support the common assumption that a large fraction of the available, legal size, male crabs are harvested each year; however, we noted regular changes in this fraction and also that it is rarely as high as previously assumed. In central California, annual exploitation rate was 92% during 1951–56 and declined to 72% following the collapse of the fishery. In northern California the annual exploitation rate varies with the 10-yr cycle of catch: 69% during the last few high catch years of each cycle, 84% in the first low catch year, and 54% during remaining low catch years and the first high catch year. The second high catch years are exceptions to a high exploitation rate. CPUE was saturated (i.e. did not decline) throughout the 1957 and 1977 fishing seasons. The large size of male crabs in the third and fourth high catch years also indicates high escapement in the second high catch years. Individual year-classes apparently may dominate the fishery for several years. This indicates that the time series of population abundance and recruitment is not as smoothly cyclic as the catch record.Key words: dungeness crab, Cancer magister, abundance, recruitment, catch per unit of effort

scholarly journals Dietary replacement of fish meal by defatted and fermented soybean meals with taurine supplementation for pompano fish: effects on growth performance, nutrient digestibility, and biological parameters in a long-term feeding period

2020 ◽  
Vol 98 (12) ◽  
Author(s):  
Hung Phuc Nguyen ◽  
Thinh Van Do ◽  
Hau Duc Tran
Keyword(s):  
Growth Performance ◽  
Soybean Meal ◽  
Fish Meal ◽  
Basal Diet ◽  
Nutrient Digestibility ◽  
Biological Parameters ◽  
Feeding Period ◽  
Taurine Supplementation ◽  
Fermented Soybean

Abstract A 16-wk growth trial was conducted to examine the effects of dietary replacement of fish meal by defatted soybean meal (SBM) and fermented soybean meal (FSBM) with taurine supplementation on growth performance, nutrient apparent digestibility coefficient (ADC) and biological parameters of pompano fish. The FSBM was produced by fermenting SBM with Lactobacillus spp. Seven isonitrogenous and isoenergetic diets were formulated to replace 35% or 50% of fish meal by SBM or FSBM with taurine supplementation. The diets are denoted as follows: FM, SBM35, SBM35T, FSBM35T, SBM50, SBM50T, and FSBM50T. The FM (the basal diet) contained fish meal as a main source of dietary protein. Taurine was supplemented to SBM35T, FSBM35T, SBM50T, and FSBM50T at the level of 15 g/kg diet. Pompano juveniles with an initial body weight (BW) of 80 g reared in floating net cages were fed the experimental diets twice daily for 16 wk. Results showed that the final BW, weight gain, and feed conversion ratio of fish fed SBM35 and SBM50 were significantly lower than those of fish fed FM (P < 0.05), indicating that the replacement of fish meal by SBM at the rate of 35% in the diet is excessive for pompano. Supplementation of taurine to the SBM-included diets significantly increased growth performance and feed utilization (P < 0.05); however, these diets did not restore the performance back to a level equivalent to that of fish offered the basal diet. Meanwhile, fish fed FSBM35T had comparable growth and feed performances to those fed FM. Hematocrit values, total biliary bile acid levels, whole body lipid contents, and tissue taurine concentrations of fish fed SBM35 and SBM50 were the lowest among the treatments, but these parameters were improved by taurine supplementation and FSBM inclusion in the diet. Taurine supplementation increased lipid ADC, and SBM fermentation slightly enhanced both lipid and protein ADCs of the fish. These findings suggest that the combination of FSBM and taurine supplementation is an effective way to improve growth performance, nutrient digestibility, and biological parameters, and that FSBM with taurine supplementation can replace 35% of fish meal in pompano diets without any negative effects on growth and feed performances in a long-term feeding period.

scholarly journals Growth and population biology of the sand-bubbler crab Scopimera crabricauda Alcock 1900 (Brachyura: Dotillidae) from the Persian Gulf, Iran

2021 ◽  
Vol 82 (1) ◽  
Author(s):  
Sana Sharifian ◽  
Vahid Malekzadeh ◽  
Ehsan Kamrani ◽  
Mohsen Safaie
Keyword(s):  
Persian Gulf ◽  
Population Biology ◽  
Slow Growth ◽  
Carapace Width ◽  
Population Data ◽  
Natural Mortality ◽  
Frequency Distributions ◽  
Iranian Coast ◽  
The Mean ◽  
The Persian Gulf

Abstract Background Dotillid crabs are introduced as one common dwellers of sandy shores. We studied the ecology and growth of the sand bubbler crab Scopimera crabricauda Alcock, 1900, in the Persian Gulf, Iran. Crabs were sampled monthly by excavating nine quadrats at three intertidal levels during spring low tides from January 2016 to January 2017. Results Population data show unimodal size-frequency distributions in both sexes. The Von Bertalanffy function was calculated at CWt = 8.76 [1 − exp (− 0.56 (t + 0.39))], CWt = 7.90 [1 − exp (− 0.59 (t + 0.40))] and CWt = 9.35 [1 − exp (− 0.57 (t + 0.41))] for males, females, and both sexes, respectively. The life span appeared to be 5.35, 5.07, and 5.26 years for males, females, and both sexes, respectively. The cohorts were identified as two age continuous groups, with the mean model carapace width 5.39 and 7.11 mm for both sexes. The natural mortality (M) coefficients stood at 1.72 for males, 1.83 for females, and 1.76 years−1 for both sexes, respectively. The overall sex ratio (1:0.4) was significantly different from the expected 1:1 proportion with male-biased. Recruitment occurred with the highest number of annual pulse once a year during the summer. Conclusions The results, which show slow growth, emphasize the necessity of proper management for the survival of the stock of S. crabricauda on the Iranian coast of the Persian Gulf.

Population Structure of Dungeness Crab (Cancer magister) in British Columbia

2008 ◽  
Vol 27 (4) ◽  
pp. 901-906 ◽  
Author(s):  
Terry D. Beacham ◽  
Janine Supernault ◽  
Kristina M. Miller
Keyword(s):  
British Columbia ◽  
Population Structure ◽  
Dungeness Crab ◽  
Cancer Magister

scholarly journals Fourth Ageism: Real and Imaginary Old Age

Societies ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 12
Author(s):  
Paul Higgs ◽  
Chris Gilleard
Keyword(s):  
Older People ◽  
Long Term Care ◽  
Social Representations ◽  
Later Life ◽  
Chronological Age ◽  
Biological Parameters ◽  
Term Care ◽  
The Impact ◽  
State Responses

This paper is concerned with the issue of ageism and its salience in current debates about the COVID-19 pandemic. In it, we address the question of how best to interpret the impact that the pandemic has had on the older population. While many feel angry at what they see as discriminatory lock-down practices confining older people to their homes, others are equally concerned by the failure of state responses to protect and preserve the health of older people, especially those receiving long-term care. This contrast in framing ageist responses to the pandemic, we suggest, arises from differing social representations of later life, reflecting the selective foregrounding of third versus fourth age imaginaries. Recognising the tension between social and biological parameters of ageing and its social categorisations, we suggest, may offer a more measured, as well as a less discriminatory, approach to addressing the selective use of chronological age as a line of demarcation within society.

An Alternative Perspective on Recruitment Overfishing and Biological Reference Points

1987 ◽  
Vol 44 (4) ◽  
pp. 913-918 ◽  
Author(s):  
M. P. Sissenwine ◽  
J. G. Shepherd
Keyword(s):  
Fisheries Management ◽  
Reference Point ◽  
Reference Points ◽  
Fishing Mortality ◽  
Alternative Perspective ◽  
Conventional Models ◽  
Definition Of ◽  
Yield Per Recruit ◽  
Spawning Biomass

Biological reference points are used to guide fisheries management decisions. The reference points most often used are expressed in terms of fishing mortality rate (F). Fmsy relates to the maximization of sustainable yield. In principle, it is a most useful reference point, but in practice it is difficult to estimate. Fmax and F0.1 relate to certain levels of yield per recruit and are easily estimated, but they ignore conservation of the resource. Recruitment overfishing has usually been understood to occur when a population has been fished down to a point where recruitment is substantially reduced or fails. It has not been used as a basis for a biological reference point because the definition is vague and cannot be readily related to fishing mortality. Levels of spawning biomass below which recruitment seems to be reduced have been used, but their determination from available data is usually difficult and controversial. We propose an alternative definition of recruitment overfishing in terms of the level of fishing pressure that reduces the spawning biomass of a year class over its lifetime below the spawning biomass of its parents on average. Conventional models and types of data can be used to determine this level of F, denoted as Frep, which clearly relates to the replacement of spawning biomass and thus to sustainability of a population and yield in the long term.

scholarly journals POPULATION DYNAMICS OF MALAYAN LEAF FISH (Pristolepisgrooti Blkr.) IN RANAU LAKE, SOUTH SUMATRA

2018 ◽  
Vol 24 (2) ◽  
pp. 125
Author(s):  
Sevi Sawetri ◽  
Subagdja Subagdja ◽  
Dina Muthmainnah
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Length Frequency ◽  
Lake Ecosystems ◽  
Exploitation Rate ◽  
Length Frequency Data

The Malayan leaf fish or locally named as kepor (Pristolepis grooti) is one of important biotic components in Ranau Lake ecosystems. This study aimed to estimate population dynamic and exploitation rate of kepor in Ranau Lake, South Sumatera. The population parameters are estimated based on length frequency data which were collected in March to October 2013. Growth parameters and fishing mortality rates were calculated using FiSAT software package. The results showed that kepor’s growth was negative allometric, which tended to gain length faster than weight. Kepor population was dominated (42%) by individual length of 10.0 to 11.0 cm. Predicted length infinity (L) was 17.28 cm with high value of growth rates (K) of 1.4 year-1. The natural mortality rate (M) is 2.57 year-1, the fishing mortality rate (F) is 5.36 year-1 and total mortality rate (Z) is 7.93 year-1. The exploitation rate of Malayan leaf fish in Ranau Lake (E = 0.68 year-1) has passed the optimum score.  

scholarly journals Microbiological Characteristics of Dungeness Crab (Cancer magister)1

1975 ◽  
Vol 30 (1) ◽  
pp. 72-78
Author(s):  
J. S. Lee ◽  
D. K. Pfeifer
Keyword(s):  
Dungeness Crab ◽  
Cancer Magister ◽  
Microbiological Characteristics

An Analysis of Acid-Base Disturbances in the Haemolymph Following Strenuous Activity in the Dungeness Crab, Cancer Magister

1979 ◽  
Vol 79 (1) ◽  
pp. 47-58
Author(s):  
D. G. McDONALD ◽  
B. R. McMAHON ◽  
C. M. WOOD
Keyword(s):  
Lactate Concentration ◽  
Dungeness Crab ◽  
Acid Base ◽  
Cancer Magister ◽  
Rapid Release ◽  
Strenuous Activity ◽  
Lactate Levels ◽  
Acid Base Disturbance ◽  
Base Disturbance

Enforced activity causes a marked depression of haemofymph pH in Cancer magister. Both lactate concentration and PCOCO2 of the haemolymph are elevated immediately following exercise but resting PCOCO2 is restored within 30 min whereas resting lactate levels are not restored for at least 8 h. The haemolymph acid-base disturbance is caused largely by elevated haemolymph lactate levels but a Davenport analysis based on measurements of pH and total CO2 reveals a marked discrepancy between the amount of metabolic acid buffered by the haemolymph and the lactate anion concentration. This appears due to a more rapid release of lactate from the tissues than H+ ions produced with lactate.

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