Differing response patterns of pelagic and demersal fish assemblages to the late-1980s regime shift in the Japan Sea

Transcription

1 PICES 14th Annual Meeting, CCCC/CFAME Topic Session (S4) Vladivostok, Oct. 4, 25 Differing response patterns of pelagic and demersal fish assemblages to the late-198s regime shift in the Japan Sea Yongjun Tian, Hideaki Kidokoro and Tatsuro Watanabe Japan Sea National Fisheries Research Institute, Fisheries Research Agency (FRA), Niigata, JAPAN 1

2 Outlines of This Study 1. Backgrounds and objectives 2. Data and methods 3. Late 198s oceanic regime shift in TWC 4. Variation patterns of pelagic and demersal fish assemblages: analysis of fisheries statistics data ( ) 5. Changes in the abundance and distribution of demersal species: analysis of Offshore Trawl Data ( ) 6. Summary and conclusions 2

3 5 45 Asian Monsoon RUSSIA Aleutian Low Cold LC Water Species Subarctic Circulation Atka mackerel, walleye Decadal Scale? pollock, Pacific cod, etc. 4 PF ENSO 35 3 TC Subtropical Circulation KOREA ENSO-scale? 2m 2m JAPAN 2m Warm Water Species Tunas, yellow tail, Jack mackerel, common squid, etc

4 Environmental impacts on the fish community in the Japan Sea Mean Trophic Level Fish community (index) is abruptly changed around late 198s and largely associated with oceanic regime shift. Tian et al. (in press) What is the response of different fish assemblages? 4

5 Differences in life history characteristics Warm Water Species Cold Water Species Distribution depth <2m (coastal and continental shelf water ) >2m (deep water) Climate system (main distribution) Subtropical (south of polar front Subarctic (north of polar front) Current system Tsushima Warm Current Cold Current (water layer) (surface water) (deep water) Life span < 1 years (short-lived) >1 years (long-lived) Main Pelagic Pacific sardine, anchovy, (indicator) species (migratory) mackerel, albacore, tunas, sharks yellowtail, common squid Demersal Silver & crimson seabream, deepsea smelt, largehead haretail, willowy flounder, pointhead flounder Pacific herring, salmons, Pacific cod, walleye Pollack, tanner crab, pink shrimp, flathead flounder, witch flounder 5

6 TWO OBJECTIVES 1. To identify the variability in the pelagic and demersal Final fish Goal assemblages To understand the function and structure of the ecosystem toward ecosystem-based fisheries management 2. To unravel the response patterns of these fish assemblages to the late-198s oceanic regime shift in the Japan Sea 6

7 Data and Methods 1. Catch statistics: : 55 species items, 9% of total catches 2. Japan Sea Offshore Trawl Data: : 28 demersal species, catches and CPUE with spatial resolution of 1 minutes 3. Oceanographic data (SST): grid data set from JMA 4. 5 & 2 m depth water temperature: : an indicator of Tsushima Warm Current 5. Principal Component Analysis (PCA) and GIS Approach 7

8 Spatial differences in winter SSTs 46 N (WIN) 46 N (WIN) 44 N 42 N N 42 N Regime difference: N N N 36 N 38 N 36 N mean of N 32 N 197s 25 5km 3 N 124 E 126 E 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 144 E 146 E 34 N 32 N 199s 25 5km 3 N 124 E 126 E 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 144 E 146 E 46 N 44 N DIFF.(WIN) mean f N 44 N (WIN) N 44 N 2-5(WIN) N 4 N N N N 4 N N N 38 N 38 N 34 N 36 N 36 N 32 N 34 N 32 N 198s 25 5km 3 N 124 E 126 E 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 144 E 146 E 34 N 32 N 2s 25 5km 3 N 124 E 126 E 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 144 E 146 E 25 5km 3 N 124 E 126 E 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 144 E 146 E Decadal mean - 3 years ( ) mean 8

9 Indicator of Tsushima Warm Current 1. Late 198s 5 m depth water temperature (winter) Anomalies ( ) Anomalies (winter) regime mean

10 ly changes in 2m depth water temperature by longitude and season E 1-Winter 3 月 4-Spring 6 月 7- Summer 9 月 1-12 Autumn 月 E 1- Winter 3 月 4- Spring 6 月 7-Summer 9 月 1-12 Autumn 月 Mid-197s global regime shift is not evident Late-198s regime shift is evident: 月 1-3 月 E 4-6 月 E 4-6 月 月 7-9 月 it occurred not only in the surface Tsushima 1-12 月 1-12 月 6 warm water, but also in deep water

11 Catch (thousand metric tons) Catch (thousand metric tons) Catches Trend of 55 Species Items in the 2 1% 15 8% 1 6% 4% 5 2% Japan Sea during piscivores pelagic species sardine piscivores demersal pelagic fishes species demersal fishes invertebrates invertebrates demersal pelagics sardine demersal % pelagics excluding sardine 28 warm water species 27 cold water species 11

12 PC Scores PC Scores PC Scores PCAs of 55 species: PC1=23.8 % mid 197s PC2=21.7 % PC3=15.9 % Late 198s PC Scores PC Scores PC Scores PC1=47. % PC2=2.7 % mid 197s PC3=8.4 % Pelagic (28) species Demersal (27) species Warm water 61%<---- PC % Cold water Late 198s 12

13 Large Predatory Warm Water Species Anomalies ( ) Catch anomalies (thousand tons) Catch anomalies (thousand tons) Tuna 5 m depth water temperature (winter) Yellow tail Anomalies (winter) regime mean

14 Demersal Cold(Deep) Water Species Catch anomalies (thousand tons) Walleye pollock Catch anomalies (thousand tons) Cold regime 3 2 Increase in abundance 1 (Expansion of distribution) Warm regime Crabs Decrease in abundance (Reduction of distribution) Catch anomalies (thousand tons) Pink shrimp

15 Offshore Bottom Trawl : Target species No Japanese Name Scientific Name English Name Depth (m) Life span (years) Current 1 マダラ Gadus macrocephalus Pacific cod 2-3 >12 CW 2 スケトウダラ Theragra chalcogramma Walleye pollock 1-5 >11 CW 3 ホッケ Pleurogrammus azonus Arabesque greenling <2 >8 CW 4 ハタハタ Arctoscopus japonicus Japanese sandfish CW 5 サメ エイ ( アブラSqualus acanthias Piked dogfish >1 CW 6 ハツメ Esbastes owstoni Owenton's rockfish 19-3 >1 CW 7 ヒレグロ Glyptocephalus stelleri witch flounder 2-3 >12 CW 8 アカガレイ Hippoglossoides dubius flathead flounder 15-5 >1 CW 9 マガレイ Pleuronectes herzensteini brown sole 3-13 >1 CW 1 その他のカレイ Pleuronectidae other righteye flounder CW 11 ホッコクアカエビ Pandalus borealis Pink shrimp CW 12 ズワイガニ Chionoecetes opilio Tanner crab 2-5 >1 CW 13 ソウハチ Hippoglossoides pinetorum pointhead flounder WW 14 ムシガレイ Eopsetta grigorjewi shotted halibut <14 >1 WW 15 ヤナギムシガレイ Tanakius kitaharai willowy flounder 8-15 >1 WW 16 ニギス Glossanodon semifasciatus Deepsea smelt <2 5 WW 17 ヒラメ Paralichthys olivaceus bastard halibut <15 >1 WW 18 マダイ Pagrus major Silver seabream <1 >1 WW 19 チダイ Evynnis japonica crimson seabream 3-13 >6 WW 2 キダイ Dentex tumifrons deepsea snapper <2 >8 WW 21 エソ Synodontidae Lizardfish <12 <4 WW 22 グチ ( シログチ ) Sciaenidae (Argyrosomus a Croaker ? WW 23 マアジ Trichiurus japonicus Horse mackerel <2 4 WW 24 カナガシラ Lepidotrigla micropetera redwing searobin WW 25 タチウオ Trichiurus japonicus Largehead hairtail WW 26 アカムツ Doederleinia berycoides blackthroat seaperch (Female) WW 27 イカ類 Squids <2 <2 WW 28 タコ類 Octopus <2 WW CW: Cold Water WW: Warm Water 12 cold water species: Deep water Long-lived Northern distribution 14 warm water species: Coastal and continental shelf Short-lived Southern distribution 15

16 Offshore Bottom Trawl : Catch and CPUE CATCH Offshore Central Southwestern 42 N 41 N 4 N Offshore Catch in tons N 38 N Central 37 N 1 Southwestern 36 N N 1 2km 34 N 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E Number of hauls EFFORT Offshore Central Southwestern CPUE (kg/haul) CPUE Central Southwestern Offshore

17 Changes in compositions 1% 1% 8% Offshore 8% Proportion 6% 4% 2% Warm Cold Proportion 6% 4% 2% Warm Cold % % 8% % % 8% Proportion 6% 4% 2% Central Warm Cold Proportion 6% 4% 2% Southwestern Warm Cold % % 8% % N 41 N 4 N Offshore Proportion 6% 4% 2% Total Warm Cold 39 N 38 N 37 N 36 N Southwestern Central % N 1 2km 34 N 128 E 13 E 132 E 134 E 136 E 138 E 14 E 142 E 17

18 PCAs of demersal species from offshore trawl fisheries data PC1=32.6% PC2= PC3=1.6% PC1-3: 69% of total variance PC1: changed around late 198s 18

19 CPUE CPUE CPUE for four cold water species 6 6 Wallaye pollock Pacific cod Central 16 Southwestern distribution CPUE( Southwestern) CPUE( Southwestern) CPUE CPUE 3 1 Witch flounder Central Southwestern During warm regime, CPUE of Central 1 the these Southwestern cold 1 water 1 species in the southwestern 1979 region is decreased; while CPUE in Flathead flounder 35 3 northern regions maintained Central in 25 Southwestern 2 a relative high level: indicating 15 1 a reduction of southwestern CPUE( Southwestern) CPUE( Southwestern) Cold Warm Cold Warm 19

20 CPUE for four warm water species CPUE CPUE Redwing searobin Willowy flounder Central Central During warm.4 regime, CPUE Southwestern of.6 Southwestern the these warm.2 water species largely increased not only in the CPUE( Southwestern) Pointhead flounder Deepsea snapper Central northern regions: indicating.8 Central.12 Southwestern 15 Southwestern northward 1 expansion of distribution and.2 increase in abundance level CPUE( Southwestern) CPUE southwestern region but also in CPUE CPUE( Southwestern) CPUE( Southwestern) Cold Warm Cold Warm 2

21 Walleye pollock Pacific cod 1982 cold 1997 warm 1%~ 1%~.1%~.1%~ 21.1%~

22 Pointhead flounder Flathead flounder 1982 cold 1997 warm 1%~ 1%~.1%~.1%~.1%~ 22

23 CONCLUSIONS An oceanic regime shift from cold to warm water is identified in Tsushima Warm Current Region in late-198s. Both the pelagic and demersal fishes show decadal variation patterns and changed with the late-198s oceanic regime shift. Response patterns are different between cold and warm water species 23