Movements of satellite-tagged false killer whales around the main - PowerPoint PPT Presentation

Movements of satellite-tagged false killer whales around the main Hawaiian Islands: implications for management Robin W. Baird 1 , Gregory S. Schorr 1 , Daniel L. Webster 1 , Daniel J. McSweeney 2 , M. Bradley Hanson 3 , and Russel D. Andrews 4 1 Cascadia Research Collective, Olympia, WA USA 2 Wild Whale Research Foundation, Holualoa, HI USA 3 Northwest Fisheries Science Center, Seattle, WA USA 4 Alaska SeaLife Center and University of Alaska, Fairbanks, AK USA Deron Verbeck

Funding support Southwest Fisheries Science Center Northwest Fisheries Science Center Pacific Islands Fisheries Science Center U.S. Navy (via WHOI, SWFSC, Scripps) Wild Whale Research Foundation Dolphin Quest Other assistance/photos J. Aschettino, J. Barlow, A. Bendlin, T. Cullins, M. Deakos, A. Douglas, A. Gorgone, D. Holzer G. Legay, E. Oleson, D. Perrine, D. Roberts, M. Sakai, D. Salden Deron Verbeck

Background on false killer whales in Hawai‘i • Smallest abundance estimate of 18 species of odontocetes in Hawaiian waters (Barlow 2006) • Two genetically isolated populations (island- associated and open-ocean; Chivers et al. 2007) • Island-associated population small (estimated 123 individuals, CV = 0.73; Baird et al. 2005) • Multiple lines of evidence suggest the island- associated population has declined substantially over the last 20 years (Reeves et al. 2009) • Causes unknown, but…. Deron Verbeck

• Feed primarily on large game fish that are the target of commercial and recreational fisheries • Regularly take fish off lines Prey observed taken in Hawai‘i: Skipjack tuna Wahoo/Ono Mongchong Yellowfin tuna Mahimahi Threadfin jack Swordfish Both insular and offshore Jamie Barlow/PIFSC

Evidence for fishery interactions Three individuals from insular population (3.75% of catalog) with major dorsal fin disfigurements Disfigurement rates in 13 populations of 8 species ranged from 0.0 to 0.85% (median = 0.0%), indicating Hawai‘i insular population rates of fishery interactions high (Baird and Gorgone 2005)

Hawaiian longline fishery • Largest fishery in Hawai‘i • Rapid expansion in late 1980s/early 1990s 160 140 120 # longline vesels 100 80 60 40 20 # longline vessels 0 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Y ear

Hawaiian longline fishery • Largest fishery in Hawai‘i • Rapid expansion in late 1980s/early 1990s • Only fishery with observer program - 20% observer coverage in deep-set (tuna) fishery since 2001, 100% in shallow-set (swordfish) fishery since 2001 160 25 140 20 120 # longline vesels # hooks (millions) 100 15 ~4% 80 10 60 40 5 # longline vessels 20 # hooks total (million) 0 0 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Y ear

Hawaiian longline fishery • Fishery exclusion zone put in place in 1992 • Boundary contracts 4 months of the year • ~25% of boundary within 45-50 km during October through January 24 23 F eb-Sep long-line exclusion boundary O ct-Jan long-line Latitude (degrees N) 22 exclusion boundary 21 Year-round long-line 20 exclusion boundary 19 E E Z boundary 18 -162 -161 -160 -159 -158 -157 -156 -155 -154 Longitude (degrees W )

Bycatch in the longline fishery 1997-2009 • False killer whale most 32 frequently ‘taken’ 30 species 28 H awaiian Islands E E Z 26 • Bycatch rates have 24 exceeded sustainable 22 level (PBR) since first Latitude (degrees N) 20 available (2000) 18 • Estimated 124 killed in 16 Hawai‘i EEZ waters 14 from 1997-2007 12 Johnston Atoll E E Z • Bycatch under- 10 P almyra Atoll E E Z estimated: some 8 6 individuals not 4 identified to species, 2 and lost gear -183 -181 -179 -177 -175 -173 -171 -169 -167 -165 -163 -161 -159 -157 -155 -153 -151 -149 -147 Longitude (degrees W ) • Bycatch by foreign vessels outside of U.S. False killer whale serious injuries, mortalities, and non- waters serious injuries in longline fishery

What do we know about movements? • Island-associated individuals move regularly among islands (rate unknown) • Nothing known about movements/use of windward sides • Furthest offshore island-associated population documented 32 km 22.5 K aua'i 22 O 'ahu 21.5 ) Latitude (degrees N 21 Maui 20.5 20 H awai'i 19.5 19 18.5 -161 -160 -159 -158 -157 -156 -155 Longitude (degrees W) Offshore population (known or suspected) Sightings and effort from surveys Insular population (known) 2000-2009, 52,320 km effort

Three main questions Examine movements of false killer whales to assess: • what biases might exist for mark-recapture estimates using photo-identification data from different islands? • do individuals from the insular population move far enough offshore to interact with the offshore long-line fishery? • does the range of the insular population overlap with the offshore (“pelagic”) population? 24 23 F eb-Sep long-line exclusion boundary O ct-Jan long-line Latitude (degrees N) 22 exclusion boundary 21 Year-round long-line 20 exclusion boundary 19 E E Z boundary 18 -162 -161 -160 -159 -158 -157 -156 -155 -154 Longitude (degrees W )

Tag design based on Andrews et al. 2008 Wildlife Computers Spot 5 ARGOS-linked location only 42 grams Medical grade titanium darts Transmitting 7-18 hours/day Deployed by pneumatic rifle Dorsal fin or dorsal ridge Range 2-10 m

After tagging Photos compared to long-term catalog to confirm population identity Tag data processed through Douglas Argos-Filter to remove unrealistic locations (based on rate and bearing of movements) Filtered data processed in Arc GIS to assess habitat use (depth, distance from shore, distance from 200 m isobath) on windward and leeward sides and among islands

False killer whales satellite tagged Period # # days # days Population tagged individuals span locations identity Aug 2007 3 32 29 Insular Jul 2008 7 76 76 Insular Dec 2008 1 54 54 Insular Oct 2009 5* 45* 45 Insular Apr 2008 1 15 5 Offshore *Three still transmitting Doug Perrine

Movements of false killer whales (1 per group) Period Distance from Depth (m) Minimum Maximum tagged shore (km) distance distance moved Median (range) traveled from tagging Median (km) location (km) (range) 14.1 Aug 07 (1.6 – 95.9) 20.5 Jul 08 (0.9 – 83.1) 22.7 Dec 08 (2.7 – 87.3) 122.8 Apr 08 (62.1 – 210.0) Doug Perrine

Movements of false killer whales (1 per group) Period Distance from Depth (m) Minimum Maximum tagged shore (km) distance distance moved Median (range) traveled from tagging Median (km) location (km) (range) 14.1 597 Aug 07 (1.6 – 95.9) (46 – 4,833) 20.5 827 Jul 08 (0.9 – 83.1) (46 – 4,767) 22.7 1,052 Dec 08 (2.7 – 87.3) (94 – 4,847) 122.8 3,844 Apr 08 (62.1 – 210.0) (1,474 – 4,747) Doug Perrine

Movements of false killer whales (1 per group) Period Distance from Depth (m) Minimum Maximum tagged shore (km) distance distance moved Median (range) traveled from tagging Median (km) location (km) (range) 14.1 597 Aug 07 2,612 (1.6 – 95.9) (46 – 4,833) 20.5 827 Jul 08 3,010 (0.9 – 83.1) (46 – 4,767) 22.7 1,052 Dec 08 5,653 (2.7 – 87.3) (94 – 4,847) 122.8 3,844 Apr 08 (62.1 – 210.0) (1,474 – 4,747) Doug Perrine

Movements of false killer whales (1 per group) Period Distance from Depth (m) Minimum Maximum tagged shore (km) distance distance moved Median (range) traveled from tagging Median (km) location (km) (range) 14.1 597 Aug 07 2,612 420.1 (1.6 – 95.9) (46 – 4,833) 20.5 827 Jul 08 3,010 329.9 (0.9 – 83.1) (46 – 4,767) 22.7 1,052 Dec 08 5,653 330.7 (2.7 – 87.3) (94 – 4,847) 122.8 3,844 Apr 08 (62.1 – 210.0) (1,474 – 4,747) Doug Perrine

Offshore false killer whale satellite tagged in April 2008 20.4 Tagged 123.8 km offshore P cTag4 20.2 Long-line fishery boundary Locations on 5 days over 15 day 20 span Latitude (degrees N) 19.8 Apr 23 H awai'i Closest point to shore 62.1 km 19.6 Furthest distance offshore 210 km 19.4 M ay 5 Apr 24 Jaggar 19.2 Apr 22 Apr 22 Moved inshore of longline fishery S eamount AM P M boundary 19 Apr 25 18.8 -158.2 -157.8 -157.4 -157.0 -156.6 -156.2 -155.8 Longitude (degrees W ) Group genetically confirmed as offshore population