1. Historical and recent estimates of the body-size and abundance of pelagic species taken by longline Peter Ward RAM Myers Dalhousie University EB WP-7

2. Changes in pelagic fish communities Comparison of 1990s (Hawaii) and 1950s (POFI) longline dataComparison of 1990s (Hawaii) and 1950s (POFI) longline data Species composition Species composition Size Size Catch rates Catch rates

3. Change in index of mass Bigeye tuna Silky shark Yellowfin tuna Blue shark 1950s

4. Data Features Non-target species Non-target species Size of each fish Size of each fish Hook number Hook number Depth of each catch Depth of each catch Soak time of each catch Soak time of each catch 1950s: 1950–1958,880days survey grid 1990s: 1994–2002,505days commercial fishing

5. Study area Hawaii 1950s 1990s

6. 1369 12 Month 1950s1990s

7. 1950s 1990s 02:0004:0006:0008:00 Deployment time

8. Soak time (hr) 1950s 1990s 02468101214

9. Depth (m) 050100150200250 Thermocline depth Hooks 0100020003000 Hooks per operation Key:1950s1990s 0100200300400500600 1950s 1990s Hook depth (m)

10. Depth (m) 050100150200250 Thermocline depth Hooks 0100020003000 Hooks per operation Key:1950s1990s 0 1000 2000 3000 1950s 1990s Hooks per operation

11. Summary Similar gear gear season season time of day time of dayDifferent area area depth range depth range soak time soak time number of hooks number of hooks

12. Generalized linear model: mass index = mean weight x cpue

13. Black marlin Albacore SwordfishYellowfinBigeye Silky shark Blue shark Oceanic whitetip Blue marlin Mako sharks Striped marlin Thresher sharks Sailfish SkipjackLancetfishes Wahoo Mahi mahi Barracudas Spearfish Pelagic ray Crocodile shark Pomfrets 0.010.1110100 Large predators Small species Rare species Change in mass or cpue increasedecrease

14. 020406080100 0 200 400 Yellowfin tuna size 1950s 020406080100 0 500 1500 2500 1990s Size (kg)

15. 1950s mean size (kg) 1990s mean size (kg) 04080120 0 20 40 60 Blue marlin Mako sharks Mahi mahi Change in body size

16. Change in index with size 1950s mean size (kg) Change in index of mass 04080120 0.01 0.1 1 10 Blue marlin Mako sharks Mahimahi

17. Reductions in size and cpue of large predators Reductions in size and cpue of large predators Modest change in small species Modest change in small species Appearance of several new species Appearance of several new species Reduction in index of mass Reduction in index of mass Conclusions 500