Carter and others 



Chapter 27 



Mortality in Gill Nets 



throughout the year in waters less than 80 m in depth in 

 regions 3 and 4A, or in waters less than 60 m in region 4B 

 (fig. 5). Thus, 1987 and 1990 CDFG regulations should 

 protect most birds from future gill-net mortality. No mortalities 

 of Marbled Murrelets that could be related to gill-net fishing 

 have been recorded since 1987. However, murre mortality 

 has continued in winter in northern Monterey Bay, especially 

 south of Ano Nuevo State Reserve between Waddell Creek 

 and Santa Cruz (near the border of regions 4A and 4B). 

 Westfall (pers. comm.) also reported mortality of several 

 Marbled Murrelets on sports fishing lines near Santa Cruz. 

 This mortality is important because of the small size and 

 poor health of the central California population (Carter and 

 Erickson 1992). 



Southern California - From 1983 to 1989, several thousand 

 cormorants (mainly Brandt's Cormorants, Phalacrocorax 

 penicillatus) probably were killed in gill-net fisheries in 

 Southern California (Carter, unpubl. data). Mortalities were 

 recorded both near the northern Channel Islands, as well as 

 along the mainland coast, in regions 5B and 6. Because of 

 concerns by several interest groups, gill-net fishing was 

 prohibited in state waters within 3 miles of shore in these 

 regions by CDFG regulations in January 1994, except for 

 some areas near the northern Channel Islands, where fishing 

 is still allowed outside of 1-2 miles from islands. 



No mortality of Marbled Murrelets that could be attributed 

 to gill-net and trammel-net fishing has been recorded south 

 of Monterey Bay. Small numbers of murrelets occur in 

 nearshore waters in this area during winter. These birds 

 probably represent some limited southward dispersal of birds 

 in the non-breeding season from the Central California 

 breeding population. Marbled Murrelets have not been 

 recorded at the Channel Islands. 



Discussion 



Mortality in gill nets may be one of the greatest 

 conservation problems facing the Marbled Murrelet. In Alaska 

 and British Columbia, levels of mortality need to be better 

 established, but available evidence indicates that several 

 thousands are killed annually. The large numbers of murrelets 

 killed in nets in Alaska and British Columbia has not been 

 fully appreciated in previous reviews (DeGange and others 

 1993. Mendenhall 1992, Rodway and others 1992, Sealy 

 and Carter 1984). Since these levels of mortality probably 

 have been focused on certain populations over the past few 

 decades, gill-net mortality alone may have already been an 

 important factor of the decline in Alaska and British Columbia 

 populations. Coupled with the loss of old-growth forest 

 nesting habitats and mortality from oil spills which may 

 affect the same populations, it is clear that survival of 

 populations in many areas in the center of its range may be 

 difficult if such problems continue. Lower numbers of birds 

 killed in central California and Washington also have had 

 relatively large impacts on these small populations and may 

 have contributed significantly to their potential future 

 extirpation (see Carter and Erickson 1992). 



Even the very few dead murrelets reported anecdotally 

 or from observer programs probably are significant because 

 few people (aside from fishermen) could report mortalities. 

 carcasses are discarded shortly after death and either sink or 

 are taken by predators soon thereafter, fishermen typically 

 do not divulge knowledge of such mortality due to fear of 

 affecting their livelihoods, and only a small fraction of nets 

 are examined in certain localities during monitoring programs. 

 For example, in Monterey Bay, California, only two birds 

 were noted in the observer program, whereas more than 100 

 were found on nearby beaches and 150-300 birds were 

 estimated killed over several years in the early 1980s (Carter 

 and Erickson 1992). Similarly, Carter and Sealy (1984) 

 recovered only 28 dead murrelets, but fishermen reported 

 catching larger numbers and a minimum of 175-250 murrelets 

 were estimated to have been killed in 1980 in Barkley Sound, 

 British Columbia. We feel that the large size of gill-net 

 fisheries, and their extensive coverage of almost all coastal 

 areas throughout the range of the Marbled Murrelet, places 

 gill-net mortality among the most significant problems for 

 the species. 



We suggest that a detailed examination of Marbled 

 Murrelet and other seabird mortality in all coastal gill-net 

 and seine fisheries is required throughout the range of the 

 murrelet. especially in Alaska, British Columbia, and 

 Washington. It is likely that relatively minor modifications 

 can be made to gill-net fisheries to vastly reduce mortality 

 quickly without significant impact to fisheries, by either 

 stopping fishing in small at-sea areas where murrelets are 

 aggregated, preventing night fishing in certain areas, or both. 

 Similarly, mortality or injury in seine nets probably can be 

 greatly reduced by ensuring that spaces occur between floats 

 along the top of the nets which allow murrelets and other 

 seabirds to escape from encircled nets. If populations become 

 (or are) too small, even low levels of gill-net and seine-net 

 mortality or injury will have or has a greater relative effect. 

 Under these conditions, it may be necessary to stop all 

 mortality by considering more drastic changes, including 

 stopping gill-net fishing in much larger areas, changing 

 fishing methods altogether, or both. To avoid severe 

 confrontation in the future, it is clear that this issue should 

 be addressed immediately. 



Acknowledgments 



J. Engbring (U.S. Fish and Wildlife Service), C. Haugen, 

 M. Vojkovich, and P. Wild (California Department of Fish 

 and Game), and D. McMullin, S. Benoit. and K. Lorette 

 (Department of Fisheries and Oceans Canada) provided many 

 valuable reports and comments. Additional information was 

 provided by R. Brown, T. Clockson, A.R. DeGange, C. 

 Haugen, S. Jefferies, K. Kuletz, G.S. Miller, J.F. Piatt, J. 

 Scordino, S.G. Sealy, S. Speich, T. Wahl, P. Wild, and J. 

 Wilson. G. McChesney and L.L. Long assisted figure 

 preparations. This summary has benefitted from reviews and 

 editing by A.R. DeGange, L.L. Long, J.F. Piatt, C.J. Ralph, 

 and M.G. Raphael. 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



283 



