Trap Fishing Black Cod British Columbia, 1971
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This publication is number 81 in the Technical Report Series TRAP FISHING of the Industrial Development Branch BLACK COD BRITISH COLUMBIA, 1971 - 1972 British Columbia April 1974 ... prepared by L. A. Webb and B. J. Lockner originally published by Southern Operations Branch Fisheries and ' Marine Service West Coast Vancouver Island Division Environment Canada re - published for Industrial Development Branch Fisheries and Marine Service Environment Canada Regional Division Chief R. H. Mc Ilwaine, P. Eng. ,. ,- i TABLE OF CONTENTS Page LIST OF FIGURES .......................................... iii LIST OF TABLES ........................................... iv LIST OF PLATES vi APPENDIX FIGURES ......................................... vii APPENDIX TABLES .......................................... viii INTRODUCTION ............................................. 1 HISTORY OF THE FISHERY ................................... 3 MARKET CONDITIONS ........................................ 5 METHODS .....................•............•.•......•...... 12 FISHING VESSEL AND GEAR DESCRIPTION A. The Vessel ..................................... 14 B. Deck Gear ...................................... 14 C. Sablefish Traps and Fishing Gear ............... 15 RESULTS Length frequencies of trap and trawl catches ........ 21 Size and abundance of sablefish, inlets vs. offshore ........................................ 21 Optimum soaktimes ..•................................ 24 C.P.U.E., inlets and offshore ....................... 27 Optimum fishing depths .............................. 31 Age-length analysis of sablefish .................... 34 Length-weight relationship .......................... 34 Incidence of other species in trap catches .......... 35 Incidence of foreign hooks and hook scars ........... 35 Incidence of nematodes .............................. 35 ii CONTENTS (Cont'd) Page DISCUSSION ................................................ 41 SUMMARY ................................................... 43 REFEREN CES ................................................ 45 ACKNOWLEDGEMENTS .......................................... 46 APPENDICES A. Set Locations and Catch Data for Strait of Georgia Inlet Trap Cat ches ................... 47 B. Set Locations, Catch Data and Specimen Data for Central B.C. Inlet and Northwest Coast Vancouver Island Trap Catches ............. 53 C. Trap and Tunnel Design .......................... 67 .iii LIST OF FIGURES Fip;ure Pa~e 1. Average (1970-72) northern British Columbia sablefish catch distribution by statistical area and gear type .................................. 8 2. Average (1970-72) southern British Columbia sable fish catch distribution by statistical area and gear type .................................. 9 3. Schematic drawing of the traps in a fishing sit ua t ion ........................................... 19 4. Length frequency distributions of trap caught sablefish (Areas 6, 8 and 27 May-June 1972) ......... 22 5. Typical len~th frequency distributions from trawl cauv,ht sablefish from southwest Vancouver Island (August-September 1971 and July-August 1967) ............................................... 23 6. The average number (center dot) and the range (ends of bar) of landed sablefish per trap by set for the north coast of Vancouver Island and Homfray Channel .................................. 25 7. Total sablefish trap catch by 20-fathom depth intervals (Northwest coast Vancouver Island May -J un e 1972) ...................................... 3 3 8. Relationship between length and weight of northwest Vancouver Island sablefish ................ 39 9. Relationship between length and weight of Fisher Channel sablefish ............................ 40 iv LIST OF TABLES Table Page o 1. Northeastern Pacific (north of 40 N) sablefish catch (all nations) ................................. 4 2. Monthly British Columbia sablefish landings in pounds by gear type (1970-72) .................... 7 3. Sablefish catches by statistical area and by gear type for 1970 to 1972 in CWT ................... 10 4. Mid-month sablefish price to fishermen at Vancouver, 1972 ..................................... 11 5. Set number, duration of soak and percentage of the total sablefish catch discarded during the trap fishery (North Coast Vancouver Island, Chimo No. I, May 1972) .............................. 26 6. Set number, duration of soak, landed pounds (dressed weight) and catch per unit of effort (Northwest Vancouver Island Sablefish Trap Fishery, Chimo No. I, May 1972) ..................... 28 7. Set number, duration of soak, landed pounds (dressed weight) and catch per unit of effort (Homfray Channel, Pryce Channel and Bute Inlet, Industrial Development Branch Charter, Chimo No. I, December 1971) ............................... 29 8. Set number, duration of soak, landed pounds (dressed weight) and catch per unit of effort (Jervis Inlet, Industrial Development Branch Charter, Chimo No. I, December 1971) ................ 30 9. Total pieces of sablefish trapped by 20 fathom depth intervals, total trap soakhours at each interval, numbers of sablefish discarded and landed catch in pieces by trap soakhour (North- west Vancouver Island May-June 1972) ................ 32 10. Length-at-age frequency distribution of trap caught sablefish (Northwest Vancouver Island May-June 1972) ...................................... 36 11. Sablefish (trap-caught) mean fork lengths, mean round weights and standard deviations at age (Northwest Vancouver Island May-June 1972) .......... 36 v TABLES (Cont'd) Tables Page 12. Total trap catch by species and their relative incidence (percent in catch) for the West Coast Vancouver Island (Area 27) cruise (Chimo No. I, May-June 1972) ..................................... 37 13. Total trap catch by species and their relative incidence (percent in catch) for the Strait of Georgia inlets (Areas 15 and 16), Industrial Development Branch Charter, Chimo No. I, December 1971 ...................................... 38 vi ' LIST OF PLATES Plate Page 1. Hauling aboard an unbaited trap. In the back ground the groundline is being retrieved by the power block ........................................ 16 2. Assembling and baiting the traps prior to setting. Note the groundline passing through a sheave overhead and the folded traps in the foreground ......................................... 20 vii APPENDIX FIGURES Figure Page Appendix A 1. Set locations for the Chimo No. I Industrial Development Charter (Bute Inlet, December - 1971) ............................................... 48 2. Set locations for the Chimo No. I Industrial Development Charter (Homfray Channel and Pryce Channel, December 1971) ....................... 49 3. Set locations for the Chimo No. I Industrial Development Charter (Jervis Inlet, December 1971) ............................................... 50 Appendix B 1. Set locations of the Chimo No. I during a commercial fishing operation (Whale Channel, May 19 72) ........................................... 5 4 2(a) Set locations of the Chimo No. I during a commercial fishing operation (Fisher Channel, May 19 7 2 ) ........................................... 5 5 2(b) Set locations of the Chimo No. I during a commercial fishing operation (Fitzhu~h Sound, May 1972) ........................................... 56 3. Set locations of the Chimo No. I during a commercial fishing operation (Northwest Vancouver Island, May-June 1972) .................... 57 Appendix C 1. Isometric view of a 34"x34"x8' trap ................. 68 2. Door and tunnel frame construction details .......... 69 3. Tunnel panel cutting instructions for a 34"x34"x8' trap ..................................... 70 viii APPENDIX TABLES Table Page Appendix A 1. Catch data from observations during the Industrial Development Branch Charter of the Chimo No. I (Bute Inlet, December 1971) ........................ 51 2. Catch data from observations during the Industrial Development Branch Charter of the Chimo No. I (Homfray and Pryce Channels, December 1971) ........ 51 3. Catch data from observations during the Industrial Development Branch Charter of the Chimo No. I (Jervis Inlet, December 1971) ...................... 52 Appendix B 1. Catch data from the Chimo No. I during a commercial fishing operation (Whale Channel, May 1972) .......................................... 58 2. Catch data from the Chimo No. I during a commercial fishing operation (Fisher Channel and Fitzhugh Sound, May 1972) ...................... 58 3. Catch data from the Chimo No. I during a commercial fishing operation (Northwest Vancouver Island, May and June 1972) ......................... 59 4. Trap-caught sablefish specimen data (Whale Channel, May 14, 1972) ............................. 60 5. Trap-caught sablefish specimen data (Fisher Channel, May 10, 1972) ............................. 61 6. Trap-caught sablefish specimen data (Northwest Vancouver Island, June 4-9, 1972) .................. 63 INTRODUCTION The sablefish or blackcod (Anoplopoma fimbria), a member of the skilfish family (not a true cod), inhabits the waters of the North Pacific Ocean. Active fisheries for this species occur from California to Alaska. The adult sablefish inhabits deeper waters than other groundfish, most often between depths of 70 and 500 fathoms. Spawning takes place in the late winter months, and is believed to occur in deep water off the west coast of Vancouver Island and the Queen Charlotte Islands. Large schools of small (sub legal size)l fish inhabit the shallower waters,