Size-dependent mortality formulation for isochronal fish species based on their fecundity: An example of Pacific cod (Gadus macrocephalus) in the eastern coastal areas of Korea

High prevalence of betanodavirus barfin flounder nervous necrosis virus as well as red‐spotted grouper nervous necrosis virus genotype in shellfish

“…However, the results support the premise that the prevalence tendency of BFNNV genotype is independent of the temperature of the sea surface, in contrast to RGNNV. Thus, it is possible that low viral concentrations in asymptomatic infected wild fishes like cod [genus Gadus (L.)], which is host species for BFNNV (Mao et al., ; OIE ) and which has been recently caught in large quantities in the waters near Korea (Jung et al., ), or some other endobiosis including molluscs and benthic organisms living in deep sea at consistently low water temperature condition would be one factor contributing to high prevalence of the psychrophilic group of betanodaviruses in shellfish, as BFNNV genotype caused the disease to spread to cultivated cold‐water fishes from wild (Johansen et al., ). On the other hand, all viruses included to each of the two genotypes were detected regardless of the shellfish species specificity and local relativity.…”

Estimating Age-Specific Natural Mortality for Sandfish in the Eastern Coastal Waters of Korea

“…However, it is appropriate to assume the natural mortality for adult stage of the model to be a constant value for the stock assessment. However, as bigger fish have fewer predators than smaller ones and natural mortality of larvae and juveniles is known to decrease with increasing body size [16][17][18], a size-dependent mortality model for stock assessments could make it more realistic, in particular, when small fish are also concerned [19,20]. Length-inverse mortality models have been proposed independently by several authors (e.g., [21]), and are supported by empirical analyses [20,22].…”

“…In addition, most methods of estimating size-dependent natural mortality do not take into account the reproduction capacity which can determine the life-time natural mortality. Thus, Jung et al [16] proposed a matrix projection method to estimate and validate size-dependent instantaneous rates of natural mortality for fish, based on their fecundity and growth. Their main assumption was that size-dependent natural mortality could be calculated numerically based on a steady-state hypothesis.…”

Estimating the Abundance and Fishing Mortality of Pacific Cod Gadus macrocephalus during the Spawning Season in Jinhae Bay, Korea, Using a Mark-Recapture Method

“…대구 수명은 최대 14세까지 보고되 어있으나 보통 8세까지이다 (Jung et al, 2008b). 우리나라 동 남해 대구 50% 군성숙크기는 전장 58.3 cm로 추정되었는데 3.6 세에 해당한다 (Jung et al, 2009). 산란기는 12-2월이며 암 컷 한 마리당 86만-640만 개의 알을 낳는다 (Cha et al, 2007;Lee et al, 2005).…”

“…오랜 대구 어획 역사에도 우리나라 대구에 대한 지속적인 생 물 생태 연구가 부족하여 대구 자원량이나 적정 어획 노력량 평 가와 가입량 예측이 힘들다. 대신 연령구조 모델에 필요한 산 란, 성숙, 성장, 사망 함수 특성치들이 동해 대구를 대상으로 최근 평가되었기에 (Jung et al, 2009) (Schnabel, 1938 (Schnabel, 1938): (Fig. 3).…”