[MARMAM] Oceanic Cetaceans of the Solomon Islands

Benjamin Kahn bkahn at apex-environmental.com
Sun Dec 3 20:59:22 PST 2006

Dear Marmamers,

The Solomon Islands Marine Assessment Report has just been released.  It includes a comprehensive chapter on cetaceans in the Solomon Islands, including a field assessment and literature review of the traditional dolphin hunting village of Fanalei).  The abstract is provided below.  

The full report is a fairly large document as the expedition's activities covered a suite of coral reef and marine resource assessments.  It's possible to download just the cetacean chapter (as well as other sections) from this link:

  Kahn, B. 2006. Oceanic Cetaceans and Associated Habitats in the Western Solomon Islands. In: Green, A., P. Lokani, W. Atu, P. Ramohia, P. Thomas and J. Almany (eds.) 2006. Solomon Islands Marine Assessment: Technical Report of Marine Survey - May 13 to June 17, 2004. The Nature Conservancy - Pacific Island Countries Report No. 1/06. pp 445-515.

Regards,  Benjamin Kahn.

Benjamin Kahn
APEX Environmental
Asia-Pacific Oceanic Cetacean Program

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The Solomon Islands Marine Assessment - Oceanic Cetaceans and Associated Habitats was conducted from 10 May to 16 June 2004.  Because of the broad and multi-faceted nature of the Solomon Island Marine Assessment's activities and goals, this program was not designed as a dedicated cetacean survey.  As such the Solomon Island Marine Assessment could not address certain species- or habitat-specific conservation and management issues for cetaceans - such as the estimation of relative abundances (which can only be estimated through more structured and periodic surveys).  Instead, this program was structured as a Rapid Ecological Assessment on Solomon Islands' oceanic cetaceans and associated habitats (the SI Cetacean REA) and included the following activities:  

  1.. To conduct a visual and acoustic survey on Solomon Islands' whale and dolphin species diversity, distribution, ranking of total individual count and their associated habitats (near shore, yet deep-water);
  2.. To canvass community knowledge on local cetacean sighting patterns, strandings and cetaceans' role in cultural heritage and folklore;
  3.. To conduct an on-board capacity building program on cetaceans for local scientists and marine conservationists; 
  4.. To assist with the identification of migratory corridors of national and regional importance, as well as other critical cetacean habitats; 
  5.. To strengthen national conservation policies for large cetaceans and marine bio-diversity in general;
  6.. To evaluate the potential for sustainable and responsible (sperm) whale and dolphin watch activities.

The SI Cetacean REA was conducted during 36 survey days in the central and western provinces of the Solomon Islands and included 160.0 hours of visual survey time, covering 1228.1 nautical miles.  Cetaceans were sighted on 52 separate encounters in which 815 animals were counted, belonging to 10 species.   The species sighted include (ranked by sighting frequency): Spinner dolphin (Stenella longirostris); Pantropical spotted dolphin (Stenella attenuata); Common bottlenose dolphin (Tursiops truncatus); and single sightings for the Indo-Pacific bottlenose dolphin (Tursiops aduncus); Orca or killer whale (Orcinus orca); Risso's dolphin (Grampus griseus); Rough-toothed dolphin (Steno bredanensis); Short-finned pilot whale (Globicephala macrorhynchus); Mesoplodon beaked whale (Mesoplodon sp.); Rorqual baleen whale (Balaenoptera sp. - either the common Bryde's or Sei whale;  B. brydei or B. borealis respectively).   


Acoustic surveys included 49 offshore listening stations.  In total, cetacean presence was acoustically detected on 51% of all listening stations.  Sperm whales (Physeter macrocephalus) were positively identified acoustically, bringing the total of species for the SI Cetacean REA to 11.  Acoustic contacts were dominated by oceanic dolphins, followed by sperm whales.  Both sighting frequencies and counts of individuals were dominated (>95%) by the same 3 species: spinner dolphins, common bottlenose dolphins and spotted dolphins.  Sighting and acoustic results were corrected for survey effort and an initial comparison with similar REAs in other regions was made.  There were unfavourable sighting conditions during a substantial number of days.  These were spread evenly over all SI Cetacean REA Legs.  


The SI Cetacean REA visual and acoustic results strongly indicate a relatively low cetacean species diversity and relative low abundance throughout most of the western Solomon Islands' provinces, at least during the SI Cetacean REA period.  In several areas, however, spinner and spotted dolphins were locally abundant.  This outcome needs to be further investigated, as - when confirmed by additional dedicated cetacean surveys - it has significance for management of cetacean use and fisheries interactions.  Issues highly relevant to the Solomon Islands are the traditional dolphin drives, the  licensed live dolphin captures for tourism ventures (for local 'swim with the dolphins' programs and trade/international export), and possibly the large-scale tuna purse-seine tuna fisheries in Solomon Islands' waters.  


Throughout the survey, local knowledge on cetaceans proved very valuable. Many coastal communities, such as the Shortlands and Savo Island, have important spinner dolphin resting areas at their local reef lagoons.  These preferred dolphin habitats seem stable for exceptional long periods and often have been known to villagers for over five generations.  Responsible, well regulated, wild cetacean watching may be feasible in these locations (and presumably in many more similar areas and communities not visited by the Marine Assessment.


Traditional dolphin hunting villages of Fanalei and Bita 'Ama were also visited. In Fanalei, elders explained that the traditional dolphin drive is practiced with strong cultural heritage and minimal modernisation in fishery methods. Essentially, dolphins are driven from the ocean into the local reef lagoon by creating an "acoustic net" through strategic placement of canoes around the pod and well-timed banging of rocks underwater.  The aftermath of a recent capture of spotted dolphins for a live-display facility did cause significant disturbance amongst the village and this modern influence may not be easily integrated within an otherwise largely traditional community.


Although the traditional dolphin drives in Fanalei are largely non-modernized, several aspects raise serious concerns.  The long-term disappearance of the valued melonheaded whales (robo au) in local waters, the increased effort due to population growth and new market forces clearly indicate that depletion of SI marine mammal resources can and does happen.  Hence, additional dedicated cetacean surveys need to be conducted by the SI Government to determine the sustainability of the traditional dolphin drives, and ultimately, to ensure the preservation of the unique cultural heritage of the SI.


The Bita' Ama community (a second village with a history of traditional dolphin drives) has not hunted dolphins for numerous years.  All dolphin hunting canoes - which are different in wood type and design from fishing canoes - are in a state of deterioration.   Preparations are being made by elders to build new canoes and resume traditional dolphin hunting in the northern Indispensable Strait within 2 years.  


Important cetacean habitats that have been identified are reef lagoons, especially for spinner dolphins, and the northern Indispensable Strait region, where, according to community knowledge, large baleen whales are common seasonally.  After detailed interviews with elders from Bita 'Ama it seems that the most likely species involved are blue whales.  Other anecdotal sighting information also strongly indicates that blue whales are present in these waters.  If confirmed, the Indispensable Strait region, as well as several other narrow yet deep island passages in the western Solomon Seas, are likely to function as marine migratory corridors for large cetaceans.  Such corridors (also called migratory bottlenecks) are often used by multiple species of large migratory marine vertebrates - including cetaceans, marine turtles, sharks, billfish and tuna - and have already been recognised to be of regional conservation importance in several other nations of the Indo-Pacific.  


Marine corridor conservation can be effectively achieved via habitat-based management frameworks including multi-use Marine Protected Areas.  Key issues for corridor conservation in the Indo-Pacific include fisheries interactions; especially gill and/or drift netting practices in or near corridors which may effectively cordon off a passage.  Because of the seasonal migrations of whales, dolphins and other migratory marine life, even short periods of intensive fishing with gillnets in the vicinity of corridors can result in very significant by-catch and entanglement rates.  Overall, management measures may vary substantially between corridor sites and ideally are incorporated within long-term management plans.


On several occasions during the SI Marine Assessment specific reef lagoon areas were identified where spinner dolphins were known to 'rest'.  These sites were often known by local communities for many generations, indicating long-term site fidelity.  In these locations community-based marine management approaches, in collaboration with provincial and national government agencies, may be an effective management framework to ensure these important dolphin habitats are conserved, and where feasible, regulate any economic opportunities such as local dolphin watching activities.


At the Arnavon Islands Marine Protected Area, the complete skeleton of a previously stranded false killer whale, Pseudorca crassidens, was located on a remote beach.  With help of the Conservation Officers, the bones and skull were transported to the Arnavon research station.  The 6m skeleton was assembled into an educational display at the station's entrance.  Furthermore, the Arnavons central location in the Manning Strait (one of the major marine corridors of the Solomon Islands), in combination with on-going marine conservation projects and trained staff which are permanently on-site, mean that conservation activities (i.e. monitoring) on whales and other large migratory marine life could be implemented relatively cost-effectively.  


The Gavutu live-capture dolphin facility was visited, and included a detailed tour and inspection.  The main business of the facility is a local 'swim-with-dolphin tourism' venture and international export of dolphins.  The recommendations of a recent IUCN Species Survival Commission report on the facility and dolphin trade were brought forward during discussions with staff.  In addition, an indirect - and unintended - effect of the facility may be over-exploitation of local fish stocks due to high daily food requirements for the dolphins, as well as price incentives to local fishermen.  


Key recommendations focus on additional cetacean surveys, ecological research, training and policy.  In particular, SI would benefit from additional cetacean surveys to estimate relative abundance for cetacean species of  interest and to further identify and confirm high priority areas for conservation.  In order to address the knowledge gap on SI cetaceans, it is vital to improve the local expertise and build capacity for long-term cetacean survey and ecological research programs in the Solomon Seas.  A national cetacean workshop with field-oriented training components has been agreed upon by Marine Assessment stakeholders as an effective tool to address this. Areas of interest for possible follow-up cetacean training, survey and research activities include: The Ghizo/New Georgia Group, Malaita, Indispensable Strait, Florida Islands, Fauro (Shortlands), and the St. Cruz Islands - the latter being the vast eastern-most province of the SI.  St. Cruz province has exceptional oceanic habitat diversity and consistent anecdotal sightings of large whales (including sperm whales and orcas).  Due to logistical constraints St. Cruz was not part of the area of interest for the Solomon Islands Marine Assessment. 


Lastly, SI would benefit from becoming a signature state of the Convention of International Trade of Endangered Species (CITES).  CITES is an internationally recognized mechanism to sustainably manage wildlife trade in endangered species, including cetaceans. By joining CITES the Solomon Islands would improve CITES coverage and effectiveness and in doing so would be welcomed by the wider international community.  In addition, Solomon Islands export a considerable quantity of fauna.  While most SI species as reported by CITES may sustain such a trade, there are several cases where CITES has recommended a ban on imports of several species from the Solomon Islands.  By not being a CITES member, the Solomon Islands has no mechanism to officially oppose such trade restrictions.


The Solomon Islands Marine Assessment provided a good basis for these recommendations.  In addition to the significant collection of cetacean data, it increased awareness and active participation amongst key government and non-government stakeholders, and assisted with the development of local capacity that may be involved in future projects on Solomon Islands' diverse whale and dolphin species and habitats.  

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