Estimation of natural mortality and exploitation rates of whelk Neptunea arthritica by multiple tagging experiment

Abstract

To estimate the natural and fishing mortality of whelk, Neptunea arthritica, a multiple tagging experiment was carried out in Shiriuchi, Hokkaido between August 1991 and March 1994. Whelks collected by trapping surveys were used in tagging experiments. All recaptured whelks were released back again so that a statistical model based on binomial distribution could be developed. Maximum likelihood estimator of the natural mortality coefficient and that of exploitation rate were determined numerically. Analysis of the recovery data show: (i) no size‐dependent mortality was observed in whelks larger than 40 mm in shell height; (ii) the daily natural mortality coefficient was 1.438 × 10−3, thus annual natural mortality rate was 41%; and (iii) the exploitation rate of commercial fishing in 1994 was approximately 77.3%. At least 53% of the total mortality was attributable to fishing in the exploited area.

A novel approach for estimation of the natural mortality of the common whelk, Buccinum undatum (L.) and role of hermit crabs in its shell turnover

“…Theoretical assessment of whelk natural mortality using parameters of the von Bertalanffy equation designed for fish (Gislason et al, 2010) and unpublished biological data collected by CEFAS for animals of 50-100 mm gives M = 0.25-0.8, depending on site and whelk size. Some in situ data also suggests that M in other whelk species of commercial size generally are similar: 0.52 in Neptunea arthritica (Suzuki et al, 2002) and 0.62 in Dicathais orbita (Phillips and Campbell, 1974).…”

Effect of water temperature and diet on growth and mortality ofNeptunea arthriticajuveniles

“…On the other hand, reports on tagging and recapture analysis revealed that annual natural mortality rate of N. arthritica reached 41% (Suzuki, Hiraishi, Yamamoto & Nashimoto 2002). Fujinaga and Nakao (1996) estimated that mortality rate in hatchlings (0–10 months of age) was around 60%.…”

Dispersion processes of the ranched striped jack Pseudocaranx dentex after release

“…This normalized likelihood function considers the effect of overdispersion φ 5–8,10 . Akaike Information Criterion (AIC) 11 was used to choose the best model in ( k + 1) nested models.…”

“…We used the likelihood that L(a,t i ,M i ,f) proposed by Kitada 7 to estimate the parameters of a, M i and t i with the maximum likelihood estimation method, which is represented as: [3] This normalized likelihood function considers the effect of overdispersion f. 5-8, 10 Akaike Information Criterion (AIC) 11 was used to choose the best model in (k + 1) nested models. If AIC changed little with k, we compared the models with a log-likelihood ratio test.…”