한수지 5(1), 65-76, 217 Original Article Korean J Fish Aquat Sci 5(1),65-76,217 생활사기반모델을이용한동해명태 (Gadus chalcogrammus) 의개체군평가 김규한 손명호 1 현상윤 * 부경대학교자원생물학과, 1 국립수산과학원제주수산연구소 A Life Stage-based Model for Assessing the Walleye Pollock Gadus chalcogrammus Population in the East Sea Kyuhan Kim, Myoung Ho Sohn 1 and Saang-Yoon Hyun* Department of Marine Biology, Pukyong National University, Busan 48513, Korea 1 Jeju Fisheries Research Institute, National Institute of Fisheries Science, Jeju 6368, Korea Since the late 199s, walleye pollock Gadus chalcogrammus fisheries in Korean waters have been considered collapsed. Although many fisheries scientists suspect that the collapse might have been triggered by overexploitation of juvenile pollock or environmental changes, such conjectures have been neither tested nor investigated, partially because of limited data on the population. There has been no survey of the population, and the ages of fish in fishery catch have rarely been identified. Instead, fishery catch data from 1975-1997 included information about two life stages, juveniles and adults, and data on catch-per-unit-effort (CPUE) during 1963-27 and those on fish length and weight during 1965-23 had been sporadically collected from commercial fisheries. To test hypotheses about the collapse of the pollock fisheries, we used a statistical linear model with juvenile CPUE as the response variable, and abiotic (e.g., water temperatures) and biotic factors [e.g., adult pollock, flatfishes (Pleuronectidae sp.), and sandfish (Arctoscopus japonicus) CPUEs] as the explanatory variables. The model results indicated that depletion of the pollock population was associated with both biotic (adult pollock and flatfishes abundance) and abiotic factors (mid-water temperatures in February and October). We further interpreted the results from ecological and biological perspectives, suggesting possible mechanisms. Key words: Pollock population depletion, Generalized linear model, Catch-per-unit-effort, Fisheries selectivity 서론 (Gadus chalcogrammus) 199. 1981 17 1995 1, 28 1.. 198 (climate regime shift) (Zhang et al., 2; Zhang and Gong, 25; Kim et al., 27).., Nishimura (1969) 2-5 C 2 m (permanent thermocline) 5 C 2 m. Gong and Zhang (1986) http://dx.doi.org/1.5657/kfas.217.65 Korean J Fish Aquat Sci 5(1) 65-76, February 217 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens (http://creativecommons.org/licenses/by-nc/3./) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Received 27 December 216; Revised 13 February 217; Accepted 14 February 217 *Corresponding author: Tel: +82. 51. 629. 5929 Fax: +82. 51.629.5931 E-mail address: shyun@pknu.ac.kr Copyright 217 The Korean Society of Fisheries and Aquatic Science 65 pissn:374-8111, eissn:2287-8815
66 김규한ㆍ손명호ㆍ현상윤 Kooka et al. (1998) 4 1 15-25 m 4-5 m. (ontogenetic vertical migration) (Yamamura et al., 22; Duffy-Anderson et al., 23; Smart et al., 213; Parker-Stetter et al., 215).. 1971 (Kim, 1978), 1975 ( : ) ( ) (Fig. 1a). Kang et al. (213) 1975-1997 91% Longline CPUE (kg basket -1 ) Catch in MT ( 1 3 ) Danish-seine CPUE (kg haul -1 ) 12 1 8 6 4 2 3 (b) 25 2 15 1 5 2 (c) 15 1 5 (a) 196 197 198 199 Year Juvenile Adult Longline Gillnet 2 21 12 1 8 6 4 2 Gillnet CPUE (kg sheet -1 ) Fig. 1. Data on fishery catches of adult and juvenile pollock Gadus chalcogrammus in the East Sea (a), and catch per unit effort (CPUE) collected from gillnet and longline fisheries (b), and Danish seine fishery (c). A sheet is a unit area of the gillnet whose width ranges from 45 m to 72 m and whose height ranges from 4 m to 4.125 m. One basket in the longline contains about 3 hooks.. 197 (recruitment to the adult population),,.,, ( ). Virtual Population Analysis (VPA) (Yabuki and Honda, 25; Mori et al., 212) (Shida et al., 27; Funamoto, 211; Funamoto et al., 213; Funamoto et al., 214). (i.e., ).,. (Generalized linear model:glm),.,, (Pleuronectidae sp.) (Arctoscopus japonicus),. 재료및방법 생물학적정보 1965 23,,,.,,,. 12,45 5,699 (47%), 2,668 (22%), 1,632 (14%), 69 (6%) 1,356 (11%)., 39 1 (1969-1972, 1986-199, 21) (Total
생활사기반동해명태개체군평가 67 length: TL) (Fork length: FL). 1973 1975, 1989, 199 722 1 7. 1 3 cm. (survey). (Fig. 2). (Table 1)., Kim and Huh (1978) ( 27 cm) 27 cm., 197 198 (i.e., 1975-1989) ( 27 cm) (> 27 cm) 9:1, 199 (i.e., 199-1997) 3:1., (1975-1997). Table 1. Annual juvenile and adult pollock Gadus chalcogrammus catches by four major pollock fisheries in Korean waters Year Adult catch by fishery (MT) Juvenile catch by fishery (MT) Danish Gillnet Longline Trawl Total Danish Gillnet Longline Trawl Total 1975 66 3,264 1,18 21 4,369 38,69 11,592 5,21 1976 241 4,45 422 62 5,175 52,621 69 16,4 69,63 1977 851 7,721 8,993 784 18,349 64,546 12 27,714 92,272 1978 796 7,11 1,681 866 1,444 52,527 23 36,322 88,872 1979 1,291 7,78 1,533 1,68 11,582 5,817 29 28,463 34,489 198 2,464 13,916 4,863 5,698 26,941 33,962 138 2 3,922 65,24 1981 1,79 18,89 2,992 5,219 46,81 47,47 16 42,296 89,782 1982 2,826 19,5 1,738 4,779 37,843 47,226 45 46,88 94,151 1983 4,4 12,78 7,624 4,177 28,585 31,485 119 24,75 55,679 1984 5,435 18,395 12,11 3,458 39,398 37,11 159 13 28,792 65,975 1985 7,534 22,892 5,817 9,96 46,23 22,22 32 21 14,67 37,15 1986 9,182 21,454 7,411 8,36 46,47 19,314 23 1 12,554 31,892 1987 4,674 5,953 5,219 3,945 19,791 8,494 2 5 4,825 13,344 1988 3,382 5,753 2,457 1,649 13,241 1,613 13 1,32 2,658 1989 4,11 6,41 2,939 2,162 15,612 6,4 4 1,236 7,64 199 2,154 4,85 1,867 1,496 9,62 13,53 82 2,34 15,619 1991 2,664 1,137 1,951 2,533 8,285 6,77 47 3,295 1,49 1992 1,71 1,612 1,914 735 5,962 3,361 19 1 1,584 4,965 1993 1,649 2,422 2,446 1,558 8,75 2,411 98 5,53 7,562 1994 1,94 2,131 3,25 527 7,2 1,252 48 1,839 3,139 1995 158 3,635 2,61 869 6,723 1,92 9 26 2,189 1996 232 2,76 1,362 662 4,332 1,821 17 1 1,79 3,629 1997 273 2,948 847 2,19 6,258 41 17 386 93
68 김규한ㆍ손명호ㆍ현상윤 CPUE 자료 1963 27,, (catch-per-uniteffort: CPUE) (Fig. 1b, 1c and Fig. 3)., CPUE.,,, CPUE CPUE. (i.e., ) (1-3 ) (1-3 ). CPUE CPUE CPUE.,., CPUE, CPUE CPUE. 반응변수 27 cm,., CPUE 2 (recruitment to the fishery). CPUE, CPUE., ( 14-27 cm) Park et al. (1978) von Bertalanffy [L t =65.4 (1 exp.223 (t+.249) )]. t, L t t (cm) von Bertanalffy FL TL FL. FL-TL, FL=.424+.959 TL (r 2 =.98, n=8189) FL 41 8 6 4 2 (a) 39 Frequency 3 (b) 25 2 15 1 5 12 (c) 1 8 6 4 2 1 2 3 4 5 6 7 Total length (cm) Fig. 2. Length-frequency distribution of walleye pollock Gadus chalcogrammus caught by gillnet (a), longline (b), and Danish seine (c) fisheries. 125 127 129 131 Fig. 3. Blocks [approximately 3 3 (nautical mile) 2 ] in dark gray where the CPUE data were collected. Those encompassed by the solid and broken lines denote major locations where gillnet and longline fisheries, and Danish seine fishery were operated, respectively. 37 35 33
생활사기반동해명태개체군평가 69 (13-25 cm) von Bertalanffy.7-2. CPUE CPUE CPUE (r>.8, P-value<.5). 1-3 6-8 CPUE CPUE.7-2. 1 1-3 1-3 1 2, 6-8 1.5-6. 1 (1-3 ) 17-2 cm (i.e., 16-19 cm) 1 (Fig. 2c), 1-3 1. t CPUE 1-3 t 2, 6-8 t 1. CPUE. 설명변수 (abiotic) 7. 7 1975 199 6 (Fig. 3). (Kim and Yoo, 27), 7. (KODC) (KODC, 211). 1973 1993 7 14 5-7 5 1 15 2 25 3 Feb Apr Depth (m) 5 1 15 2 25 3 5 1 15 2 25 Jun Oct Aug Dec 3 5 1 15 2 25 5 1 15 2 25 Temperature ( ) Fig. 4. Bimonthly vertical temperature profiles of Block 7 during 1973-1993. Each solid line indicates an annual temperature profile of every other month (i.e., February, April, June, August, October, and December).
7 김규한ㆍ손명호ㆍ현상윤 15 m -15 m 5 m (Fig. 4). (multicollinearity)..7 (P-value<.5).,, CPUE. CPUE CPUE CPUE (Spawning Stock Biomass: SSB). CPUE. CPUE CPUE CPUE. 시차적용 (Winter and Swartzman, 26). CPUE 1 2 CPUE 1 2 (timelag). CPUE Response variable Juvenile CPUE (Jan~Mar in year t) Juvenile CPUE (Jun~Aug in year t) Age-2 in year t Age-1 in year t Candidate explanatory variables Temperatures (year t-2) Adult CPUEs (Oct~Mar in year t-2) Flatfishes CPUE (Jan~Mar in year t) Sandfish CPUE (Jan~Mar in year t) Temperatures (year t-1) Adult CPUEs (Oct~Mar in year t-1) Flatfishes CPUE (Jun~Aug in year t) Sandfish CPUE (Jun~Aug in year t) Fig. 5. Diagram depicting all the variables considered for the linear model. In the candidate explanatory variables, the numbers subtracted from t (e.g., t-1 and t-2, where t denotes the year index), indicate time delays by which CPUE of juveniles at age-1 and age- 2 were used as that of juveniles at age-. 1 2 (Fig. 5). 일반화선형모델 (Generalized linear model: GLM). Y=X β+ε Y (n 1) log ( CPUE t ). n t CPUE (skewness). X (n p) (design matrix) (interaction term). p β. ε. (analysis of deviance: AN- ODEV) (Hyun et al., 214). (D) (saturated model) (proposed model) (likelihood ratio) 2 (McCullagh and Nelder, 1989; Dobson and Barnett, 28)., D = 2 (l saturated l proposed ) = 2 (l proposed l saturated ) l., D (null model). (nested model) ( D). 2 ( df) (McCullagh and Nelder, 1989; Dobson and Barnett, 28): D~ 2 df. 모델진단.. (Cook s distance), C i (Cook and Weisberg, 1982) C i =(b b (i) ) T (Χ T X)(b b (i) )/ (p MSE). i C i 1 b, b (i)
생활사기반동해명태개체군평가 71 i, MSE T. (externally studentized residual) d i. d i =e i /( MSE (i) (1 h ii )) e i i, MSE (i) i h ii (hat matrix) i. (n p 1) t 1.5 d i >t(1 /2; n p 1) (Kutner et al., 25). n, p.. (ridge trace) (mean-centering). (Variance Inflaction Factor: VIF). (ridge estimator), ^ β( )=X T X+ I) -1 X T Y (biasing parameter), ^β( ) (Hoerl and Kennard, 197)., ^β( ). 가입과정분석 SSB. CPUE., 1 6 CPUE CPUE. (i.e., CPUE),. 결과 모델의선택과진단 Table 2 1+Temp1.15_Feb+Long+Temp15_Oct+Flat+Long Temp15_Oct. Shapiro-Wilk (Shapiro and Wilk, 1965; R Core Team, 213) (Pvalue=.35) (Fig. 6), Breusch-Pagan (Breusch and Pagan, 1979; R Core Team, 213; Hothorn et al., 215) (P-value=.55) Sample quantiles 3 2 1-1 -2-3 -2-1 1 2 Theoretical quantiles Fig. 6. Quantile-quantile plot of residuals for the final model. Table 2. Model selection summary. Temp 1.15_Feb, Long, Temp 15_Oct, and Flat denote the average of water temperatures at the depths of 1 and 15 m in Feburary, longline CPUE, that of water temperatures at the depth of 15 m in October, and flatfishes CPUE, respectively Model Linear form D df ΔD Δdf P-value AIC 1 Null 15.98 24 NA NA NA 111.6 2 1 + Temp 1.15_Feb 81.16 23 24.82 1.8 16.39 3 1 + Temp 1.15_Feb + Long 53.24 22 27.93 1.1 97.84 4 1 + Temp 1.15_Feb + Long + Temp 15_Oct 42.46 21 1.78 1.21 94.19 5 1 + Temp 1.15_Feb + Long + Temp 15_Oct + Flat 35.49 2 6.97 1.47 91.7 6 1 + Temp 1.15_Feb + Long + Temp 15_Oct + Flat + Long Temp 15_Oct 26.52 19 8.96 1.11 86.43
72 김규한ㆍ손명호ㆍ현상윤. (Fig. 7a). 5 (numerical instability). Fig. 7b. (Table 3). Standardized coefficient 3 2 1-1 -2-3 3 2 1-1 -2-3 (a) (b) Temp 1.15_Feb Long Temp 15_Oct Flat Long Temp 15_Oct Temp 1.15_Feb Long Temp 15_Oct Flat Long Temp 15_Oct 5 1 15 2 25 3 Biasing parameter (θ) Fig. 7. Ridge trace plots describing trends of the estimated coefficients as a function of biasing parameters θ before (a) and after (b) mean-centering. 모델결과 (final model) (Table 3b).., (Afshartous and Preston, 211). 2 1 m 15 m., 2. 1 15 m CPUE (interaction effect) (Fig. 8). 어획의영향 3 CPUE (r>.7) 4 (r>.9) (Table 4). CPUE CPUE 1 3,, 3 4. Fig. 9 Table 3. Estimates of coefficients (Coef) of explanatory variables and their standard errors (SE) in the best model before mean-centering (a) and those after mean-centering (b). Temp 1.15_Feb, Long, Temp 15_Oct, and Flat denote the average of water temperatures at the depths of 1 and 15 m in Feburary, longline CPUE, the average of water temperatures at the depth of 15 m in October, and flatfishes CPUE, respectively Explanatory variable (a) Before mean-centering (b) After mean-centering Coef SE t P-value Coef SE t P-value Intercept -6.1 1.83-3.33. 5.16.31 16.77. Temp 1.15_Feb.45.12 3.91..45.12 3.91. Long.52.11 4.65..22.6 4.1. Temp 15_Oct 1.14.34 3.34..53.13 3.98. Flat.3.1 2.4.3.3.1 2.4.3 Long Temp15_Oct -.6.2-2.53.2 -.6.2-2.53.2
생활사기반동해명태개체군평가 73 6 Environmental effect Fishing effect 5 Temp15_Oct ( ) Juvenile CPUE (log of Kg/haul) 4 3 2 1 12 1 8 Long (kg/basket) 6 4 4 2 2 Temp 15_Oct ( ) Fig. 8. Three-dimensional plot of the interaction term, Long and Temp 15_Oct. Those two variables associated with the interaction term were mean-centered (e.g., Long c =Long-Long and Temp 15_Oct c =Temp 15_Oct-Temp 15_Oct, where the subscript c denotes the mean-centering procedure; the means of the two variables, Long and Temp 15_Oct are 9.9 kg/basket and 4.91 C, respectively).. 고찰,. (Montgomery et al., 215).,. 6 8 1 12 Temp1.15_Feb (+) Flat (+) Age- Age-1, 2 Adult Long ( ) Fig. 9. Summary for interpreting study results. The dashed arrows show pathways of significant explanatory variables and those in parentheses indicate a direction of effect (i.e., -, + and denote negative, positive and interaction effects, respectively). Areas separated by gray represent a major source of mortality on each life stage of walleye pollock Gadus chalcogrammus; environmental effect on those in white; fishing effect on those in gray.. 7 15 m. 15 m 15 m (Temp 1.15_Feb Temp 15_Oct)., 15 m. 1 15 m. Table 4. Time-lagged correlations between catch and CPUE of juvenile, and those of adult. Those in parentheses denote a type of fishery used for data collection, and values followed by an asterisk denote significant difference (P-value<.5) Data Shift value in year +1 +2 +3 +4 +5 +6 Juvenile catch Adult catch.576*.688*.836*.939*.867*.716* Juvenile CPUE (Danish seine) Adult CPUE (gillnet).28.541*.787*.672*.4.32 Adult CPUE (longline).283.55*.796*.671*.264.212
74 김규한ㆍ손명호ㆍ현상윤. (1) Temp 1.15_Feb: 2 1 m 15 m Cushing (1969). 1 m 15 m. (spring bloom) (Yamada et al., 24),., Shida et al. (27) 2 1-2, Funamoto et al. (214) 2. 1-15 m, 2., Shida et al. (27) 2. (2) Flat: 1 2.. (3) Long Temp 15_Oct: CPUE 1 15 m., 1 15 m.,..,. 1 (fall bloom) (Heintz and Vollenweider, 21)., (1) Temp 1.15_Feb.,.. Francis and Bailey (1983) Olla and Davis (199).,,. 1 15 m. (uncertainty).. CPUE (survey), CPUE 25. (variance). Park et al. (1978) von Bertalanffy (deterministic model),.. Kooka (212) von Bertalanffy Park et al. (1978), Park et al. (1978)., Kooka (212), Park et al. (1978) 1974-1978
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