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 (islandassociated 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 islandassociated 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)
Year 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
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 100 80 60 ~4% 15 10 # hooks (millions) 40 5 20 # longline vessels # hooks total (million) 0 0 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year
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 Latitude (degrees N) 23 22 21 20 Year-round long-line Oct-Jan long-line Feb-Sep long-line exclusion boundary 19 EEZ boundary 18-162 -161-160 -159-158 -157-156 -155-154 Longitude (degrees W)
Bycatch in the longline fishery 1997-2009 Latitude (degrees N) 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 Hawaiian Islands EEZ Johnston Atoll EEZ 2-183 -181-179 -177-175 -173-171 -169-167 -165-163 -161-159 -157-155 -153-151 -149-147 Longitude (degrees W) Palmyra Atoll EEZ False killer whale serious injuries, mortalities, and nonserious injuries in longline fishery False killer whale most frequently taken species Bycatch rates have exceeded sustainable level (PBR) since first available (2000) Estimated 124 killed in Hawai i EEZ waters from 1997-2007 Bycatch underestimated: some individuals not identified to species, and lost gear Bycatch by foreign vessels outside of U.S. waters
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 Kaua'i 22 21.5 O'ahu Latitude (degrees N) 21 20.5 20 19.5 Maui Hawai'i 19 18.5-161 -160-159 -158-157 -156-155 Longitude (degrees W) Offshore population (known or suspected) Insular population (known) Sightings and effort from surveys 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 Latitude (degrees N) 23 22 21 20 Year-round long-line Oct-Jan long-line Feb-Sep long-line exclusion boundary 19 EEZ 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 tagged # individuals # days span # days locations Population 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 tagged Distance from shore (km) Median (range) Depth (m) Median (range) Minimum distance traveled (km) Maximum distance moved from tagging location (km) Aug 07 14.1 (1.6 95.9) Jul 08 20.5 (0.9 83.1) Dec 08 22.7 (2.7 87.3) Apr 08 122.8 (62.1 210.0) Doug Perrine
Movements of false killer whales (1 per group) Period tagged Distance from shore (km) Median (range) Depth (m) Median (range) Minimum distance traveled (km) Maximum distance moved from tagging location (km) Aug 07 14.1 (1.6 95.9) 597 (46 4,833) Jul 08 20.5 (0.9 83.1) 827 (46 4,767) Dec 08 22.7 (2.7 87.3) 1,052 (94 4,847) Apr 08 122.8 (62.1 210.0) 3,844 (1,474 4,747) Doug Perrine
Movements of false killer whales (1 per group) Period tagged Distance from shore (km) Median (range) Depth (m) Median (range) Minimum distance traveled (km) Maximum distance moved from tagging location (km) Aug 07 14.1 (1.6 95.9) 597 (46 4,833) 2,612 Jul 08 20.5 (0.9 83.1) 827 (46 4,767) 3,010 Dec 08 22.7 (2.7 87.3) 1,052 (94 4,847) 5,653 Apr 08 122.8 (62.1 210.0) 3,844 (1,474 4,747) Doug Perrine
Movements of false killer whales (1 per group) Period tagged Distance from shore (km) Median (range) Depth (m) Median (range) Minimum distance traveled (km) Maximum distance moved from tagging location (km) Aug 07 14.1 (1.6 95.9) 597 (46 4,833) 2,612 420.1 Jul 08 20.5 (0.9 83.1) 827 (46 4,767) 3,010 329.9 Dec 08 22.7 (2.7 87.3) 1,052 (94 4,847) 5,653 330.7 Apr 08 122.8 (62.1 210.0) 3,844 (1,474 4,747) Doug Perrine
Offshore false killer whale satellite tagged in April 2008 Latitude (degrees N) 20.4 20.2 20 19.8 19.6 19.4 19.2 19 May 5 Long-line fishery boundary Apr 24 Apr 25 Apr 23 Jaggar Seamount PcTag4 Apr 22 AM Apr 22 PM Haw ai'i Tagged 123.8 km offshore Locations on 5 days over 15 day span Closest point to shore 62.1 km Furthest distance offshore 210 km Moved inshore of longline fishery boundary 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
Distance from deployment (km) Distance from deployment (km) Distance from deployment (km) 450 400 350 300 250 200 150 100 50 HIPc107 0 0 450 10 20 30 40 50 Days since deployment 400 HIPc209 350 300 250 200 150 100 50 0 0 450 10 20 30 40 50 400 Days since deployment 350 300 250 200 150 100 50 Dec 2008- Feb 2009 0 0 10 20 30 40 50 Days since deployment Jul-Sep 2008 Aug/Sep 2007 Latitude (degrees N) Latitude (degrees N) Latitude (degrees N) 23 22 21 20 19 18-161 -160-159 -158-157 -156-155 -154 23 22 21 20 19 23 22 21 20 19 Year-round long-line Year-round long-line Year-round long-line Oct-Jan long-line Longitude (degrees W) Oct-Jan long-line Oct-Jan long-line 18-161 -160-159 -158-157 -156-155 -154 Longitude (degrees W) Feb-Sep long-line exclusion boundary 18-161 -160-159 -158-157 -156-155 -154 Longitude (degrees W) Feb-Sep long-line exclusion boundary Feb-Sep long-line exclusion boundary
Individual tagged during longline boundary contraction moved closest to boundary (~16 km) 23 Dec 2008 Feb 2009 22 Oct-Jan long-line Feb-Sep long-line exclusion boundary Latitude (degrees N) 21 20 Year-round long-line 19 18-161 -160-159 -158-157 -156-155 -154 Longitude (degrees W)
Depth (m) 5000 4000 3000 2000 HIPc272 Individuals use different habitats off different islands 1000 0 Hawai'i only Other islands only 5000 HIPc172 4000 Depth (m) 3000 2000 1000 0 Hawai'i only Other islands only D. Perrine/SeaPics.com
The longline boundary contracts on the windward side, so do they use windward and leeward sides of the islands differently? Leeward (west) sides 58% of time Median depth = 674 m Median distance from shore = 14.0 km Windward (east) sides 42% of time Median depth = 608 m Median distance from shore = 11.1 km 24 Latitude (degrees N) 23 22 21 20 Year-round long-line Oct-Jan long-line Feb-Sep long-line exclusion boundary 19 EEZ boundary 18-162 -161-160 -159-158 -157-156 -155-154 Longitude (degrees W)
October 2009 5 individuals tagged off O ahu, 5 different days, 3 still transmitting link by association to insular population ~1.5 days of movements through November 4, 2 AM HST Acting as four different groups
October 2009 10 days of movements 3 individuals 9 days of movements 1 individual 8 days of movements 1 individual All groups move among islands Movements among islands rapid Furthest offshore ~110 km
Take-home messages Movements among islands rapid and frequent, thus biases from using photos from different islands probably not important in mark-recapture analyses The offshore individual moved to 62 km from shore, thus populations likely overlap All groups of island-associated individuals tagged did different things, therefore sample size insufficient to characterize island usage All groups of island-associated individuals moved far (83-110 km) offshore, furthest distance offshore during contraction of longline fishery exclusion boundary, thus island-associated population likely overlaps with longline fishery www.cascadiaresearch.org/hawaii/falsekillerwhale.htm