414 



Fishery Bulletin 105(3) 



pilot whales; however, no interactions were observed 

 in waters greater than 30 km from the 200-m isobath, 

 with the exception of one interaction observed in the 

 south Atlantic areas (Fig. 6). 



Discussion 



Interactions of marine mammals with pelagic longlines 

 are concentrated primarily in the MAB and NEC fish- 

 ing areas along the shelf break. Interaction rates were 



Mainline < 20 

 miles 



Mainline ; 20 

 miles 



Mainline < 20 

 miles 



Mainline 20 

 miles 



No catch damage 



Catch damage 



Figure 3 



Predicted (black dots) and observed (bars) interaction rates with 

 pilot whales iGlobicephala spp.) by mainline-length category 

 and observed catch damage for the Mid-Atlantic Bight fishing 

 area (A) and other fishing areas (B). Error bars indicate 957^ 

 confidence intervals of predicted values. Note the difference 

 in y-axis scale. 



consistent across the time series, with the exception of 

 the period between 1996-99. There was relatively low 

 observer coverage in the MAB fishing area during these 

 years, and the low observed interaction rates may be 

 a sampling artifact. Pilot whales and Risso's dolphins 

 are the primary species interacting with the longline 

 fishery, and mortality and serious injury of these spe- 

 cies are a significant conservation concern. Assessing 

 the impact of fishery-induced mortality on the two pilot 

 whale species (longfin and shortfin pilot whales) is dif- 

 ficult because the species cannot be distinguished in 

 either assessment surveys or when caught on 

 fishing gear. Thus, although the total fishery 

 mortality is below the PBR limit for the combined 

 species, it is possible that the longline fishery dis- 

 proportionately impacts one species. The shortfin 

 pilot whale (G. macrorhyncus) generally has a 

 more southern distribution than the longfin pilot 

 whale (G. melas), and therefore the impact of the 

 longline fishery may be more severe than current 

 stock assessments indicate. Research is currently 

 underway to determine the spatial distributions 

 of the two species in order to assess their status 

 more accurately. 



Approximately equal proportions of interac- 

 tions involve bookings versus entanglement in 

 the mainline for both species. Hooking almost 

 exclusively involves the animal being hooked in 

 the mouth. In most cases, the animal is released 

 after the gangion line is either cut or broken; 

 however the animal either trails or is entangled 

 in a significant amount of monofilament line upon 

 release. These animals are considered seriously 

 injured and likely to die, and hence they are of 

 greatest concern for conservation and manage- 

 ment agencies. Marine turtle interactions with 

 longlines also generally involve the animal swal- 

 lowing the hook or being hooked externally. 

 Therefore, developing and implementing guide- 

 lines for the removal of hooks and careful release 

 of turtles is a major focus of management efforts 

 (Watson et al., 2005). The challenges for release 

 of marine mammals are more severe because 

 larger animals can break gangion lines before 

 these animals can be brought close to the boat, 

 and there can be considerable risk of injury to the 

 vessel crew. However, the development of equip- 

 ment and protocols to more effectively remove 

 ingested hooks from marine mammals would be 

 an important step to reduce the severity of in- 

 juries. 



The shape of the hook had no effect on ma- 

 rine mammal interaction rates in these analy- 

 ses. This factor was examined closely because of 

 recent changes in longline fishery gear — changes 

 mandated to reduce the catch and mortality of 

 endangered sea turtles. As of August 2004, all 

 U.S. East Coast pelagic longline fishermen were 

 required to use larger circle hooks rather than 

 "J" hooks. In the data examined in the present 



