Population Structure and Mortality of the Neptune Whelk &lt;i&gt;Neptunea arthritica&lt;/i&gt; in Usu Bay, Southern Hokkaido

Fujinaga, Katsuaki; Nakao, Shigeru

doi:10.2331/fishsci.62.184

Cited by 6 publications

(11 citation statements)

References 14 publications

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“…Cyclic temperature shifts in whelks might cause intense feeding activity during period of warmer water while benefiting from reduced metabolic cost during cold seasons (Sanford 2002). Growth studies of N. arthritica revealed that during the first year of life, individuals could reach a size near to 20 mm in SL based on frequency analysis (Fujinaga & Nakao 1996), while Miranda, Fujinaga and Nakao (2008) estimated that 1‐year‐old males reached 20.7 mm SL and females reached 18.1 mm, based on growth marks in the operculum. This suggests that the growth attained during 6 months of experiment (20 mm maximum SL) is in close proximity to the 1‐year growth observed under wild conditions.…”

Section: Discussionmentioning

confidence: 99%

“…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%. These values are close to the results obtained here for those juveniles reared at 10 °C and fed with both diets (mortality maximum values 40% and 67% in D1 and D2 respectively), while at 15 °C mortality was higher (maximum values 83% and 87% at D1 and D2 respectively).…”

Section: Discussionmentioning

confidence: 99%

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

Miranda

Oba

Goshima

2009

Aquaculture Research

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The growth and mortality of Neptunea arthritica juveniles hatched from di¡erent egg masses (controlled conditions and ¢eld) reared at 10 and 15 1C, and provided with sardine (D1) and polychaete (D2) as foods were evaluated. Results showed that diet type and water temperature signi¢cantly a¡ect the growth and mortality. Interaction between these factors re-£ected robust relationship among them, but restricted exclusively to growth. Through the study period, juveniles treated at 10 1C showed maximum increments of 2.5 mm (shell length), 2.3 mm (shell width) and 0.25 g (body weight) from their initial size.While maximum values of those treated at 15 1C for the above-mentioned parameters were 7.6 mm, 5.5 mm and 1g respectively. In both cases, these increments were recorded for individuals fed with sardine. Mortality was signi¢cantly a¡ected by diets and water temperature, which signi¢cantly increased under D2 [10 1C (20^67%), 15 1C (70^87%)] or 15 1C [D1 (30^83%), D2 (70^87%)]. According to the results, juveniles of N. arthritica could be maintained under controlled conditions, which allows growth improvement. Mortality appears to be the limiting factor, but this could be improved by the implementation of e⁄cient culture method, basically oriented to increase the water quality. Aquaculture Research, 2009, 40, 428^436 E¡ect of water temperature and diet R M Miranda et al. E¡ect of water temperature and diet R M Miranda et al. E¡ect of water temperature and diet R M Miranda et al. r 2008 The Authors Journal Compilation r 2008 Blackwell Publishing Ltd, Aquaculture Research, 40, 428^436 E¡ect of water temperature and diet R M Miranda et al.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Miranda

Oba

Goshima

2009

Aquaculture Research

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“…In N. arthritica , a low hatching rate (18.6%) and 60% hatchling natural mortality (Fujinaga & Nakao 1996, 1998) may increase significantly the amount of broodstock required to yield a large amount of juveniles. Considering the above, conditioning of broodstock as the first step in seed production of N. arthritica is possible but may not be economically reasonable.…”

Section: Discussionmentioning

confidence: 99%

Copulation behaviour of Neptunea arthritica: baseline considerations on broodstocks as the first step for seed production technology development

2008

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Copulation trials under three different scenarios were performed aiming to study the copulation behaviour of Neptunea arthritica and determine whether broodstock maintenance is required for artificial seed production. Neptunea arthritica showed polygamy, copulating at least three times with different partners. From all males and females used in this study, 43% of them copulated at least once. Female whelks showed rejection behaviour, which generated significant difference in copulation time between rejected (13.7±10.7 min) and non‐rejected (49.7±44.7 min) males. The effect of body size on copula duration appeared to be superficial, while its effect on accumulative copulas played an important role as an indicator of copulation capacity because whelks varied in size. After first copula, males showed a contrasting tendency to mate copulated females over non‐copulated females (χ2=6.23, d.f.=1, P=0.01). Broodstock maintenance as the first step in seed production is possible but considering low mating percentage and female rejection, it would be not economically reasonable due to the considerable number of whelks required and related logistical factors.

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“…Fujinaga and Nakao estimated adult mortality as being 76.3% from May to August, 1980 in Usu Bay 9 . They proposed that natural deaths after spawning and deaths by fishing were the cause of the high mortality rate.…”

Section: Discussionmentioning

confidence: 99%

“…Reproduction and mortality are important parameters of fishery management. Growth and reproduction of N. arthritica have been well studied, 1–8 but published information about its mortality is available only in a study by Fujinaga and Nakao 9 . They estimate the mortality rate of each age class from the density of individuals; however, there is no distinction between natural mortality and fishing mortality in their study, which is important for evaluating the effect of fishing on the whelk population.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2002

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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.

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Population Structure and Mortality of the Neptune Whelk <i>Neptunea arthritica</i> in Usu Bay, Southern Hokkaido

Cited by 6 publications

References 14 publications

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

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

Copulation behaviour of Neptunea arthritica: baseline considerations on broodstocks as the first step for seed production technology development

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

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