Ethics Application
Mitigation measures to reduce entanglements of migrating whales with commercial fishing gear
Background
Whale entanglements are a key performance indicator (KPI) for the WRL fishery in Commonwealth
assessments. Entanglements in 2013 (18 in WRL gear) exceeded this KPI for the third year in a row.
The KPI breach in the proceeding season (2012, 13 entanglements) resulted in the Commonwealth
removing the WRL fishery from the List of Exempt Native Species which is a five year export approval
without conditions and issuing a two year Wildlife Trade Order (WTO) with conditions and
recommendations relating to whale entanglement. This included a condition to : "by 31 March 2014,
complete a robust evaluation of longer term operational management measures to reduce the risk of
whale entanglements, which could include the removal of some restrictions on western rock
lobsters, spatial and seasonal closures and potential gear modifications".
The WRL is almost exclusively an export fishery with an estimated annual GVP of $200 million. The
reason for increased entanglements is a combination of whale population growth (10% p/a)
(Bannister and Hedley 2001, Salgado Kent et al. 2012) and an increase in winter fishing resulting from
a relaxation of input controls after a move to quota. A closed season, removing winter fishing would
somewhat alleviate this issue, although at an economic cost to the industry as it would no longer be
able to attain the high beach prices paid in winter. This would result in a conservative loss of about
$50 million p/a in GVP. Therefore to meet the Commonwealth conditions, and still allow winter
fishing, entanglement mitigation measures are needed.
Increased information on whale migration patterns is critical to the appropriate designation of
times/area where gear modifications or spatial/temporal closures may be required. Currently, in the
absence of these data, fishers are required to use gear modifications throughout the fishery (~1000
km of coastline), for the duration of the whale migration period (~7 months, May-November). With
new information, the area/time where gear modification must be used could be refined, reducing
costs to fishers in modifying their gear by only requiring modifications where/when entanglements
are likely to occur.
Collaboration
This is a collaboration between government (DoF; Department of Parks and Wildlife), national
research bodies (Australian Antarctic Division (AAD), Murdoch University Cetacean Research Unit
(MUCRU)) and industry (WA Fishing Industry Council – WAFIC and Western Rock Lobster Council).
Objectives
1. Produce fine-spatial and temporal information on whale migrations along the west coast of
Western Australia necessary for a tailored spatio-temporal closures and/or areas for gear
modifications.
Procedures
This project uses a combination of procedures:
Telemetry :
The use of blubber/fascial-implanted satellite tags is the least invasive way of tracking whales
reliably. Alternative implantable tags are available but are significantly longer and penetrate deep
into the muscle layer.
The satellite tags are deployed via a modified pneumatic line-thrower from a distance of 4-15m. The
tag penetrates the whale’s skin and blubber until it reaches the stopper at the end of the tag. A
flexible transmitting aerial extends about 17cm from the top of the tag. The positioning of the tag is
into an area just below the dorsal fin giving the aerial maximum time at the water’s surface. The tag
is designed to transmit for a period ranging from weeks to months. The tag will fail due to electronic
malfunction, battery exhaustion or eventually tag rejection. Due to the superficial application of the
tag, it will eventually be rejected or simply fall out, usually within 6 months (Double et al. 2012).
This is a common method of satellite tracking cetaceans and has been used successfully before on
humpback whales (Double et al. 2012). All attempts and actual tag deployments are videotaped, and
the tape is reviewed each day. Videos will be available for review by regulatory agencies.
Biopsy:
Biopsy samples are collected to ascertain the sex of the tagged individual allowing sex based
movement patterns to be determined. There are marked differences in the migratory patterns of
male and female humpback whales (Brown et al. 1995), and therefore biopsies will permit a critical
examination of this. However, biopsies will also be retained and stored for possible examination as
part of future research work, where biological samples may be useful.
The skin biopsy is darted using a modified capture rifle (0.22 calibre supplied by PaxArms, Timaru).
This is a non surgical procedure and involves only brief and minor disturbance to the behaviour of
free-ranging whales. Biopsy sampling has been successfully used previously on this species (Brown et
al. 1995, Double et al. 2012). The biopsy dart is a small stainless-steel punch fitted to an arrow or
small (50 cc) floating syringe and deployed from a capture rifle. The size of the tip of the dart which
collects the sample is between 4-8mm in diameter (dependant on the tip selected) and the dart is
about 30mm in length. A metal flange or stop which sits behind the dart tip is approximately 2-3cm
in diameter and prevents penetration of the dart beyond 5-6mm into the skin and blubber and
provides recoil to dislodge the dart on contact with the whale. The actual biopsy sample removed is
approximately 2-3mm in diameter and 5-6mm in length (slightly bigger than a rice grain). In some
cases the dart may be tethered for retrieval. The force of the impact is adjusted via an adjustable gas
vent. The dart can be deployed from a distance of approximately 5-20m. The biopsy dart is cleaned
and sterilised by flaming after each collection and immersed in 70% ethanol before use.
Approaching whales for tagging / biopsy
Each whale is approached in a 5.5m rigid-hulled inflatable boat (or similar platform) to facilitate the
deployment. Strict protocols are followed to ensure that the whale is not unduly harassed during the
deployment. There are two methods of deployment employed for humpback whales:
Fast approach: initial approaches are slow and are ceased if the whale actively avoids the boat. Once
in position, a single rapid approach is made to the whale during a surfacing and the tag is deployed. If
the tag is not deployed during this fast approach, further approaches are only attempted if the whale
continues to be unconcerned by the movements of the boat. Avoidance behaviour by the whale is
used to signal the animals’ level of concern, and determines whether the attempt is terminated. Fast
approaches will not be made on animals or groups with calves.
Slow approach: where possible, drift approaches (from upwind) will be made on whales that are
resting on the surface. A tag will be deployed once the whale is within the required range. Females
with calves will not be excluded from this group as ‘slow approaches’ are relatively straight forward
with the potential for impact on the calf is negligible. Furthermore, information on the movement of
cow-calf pairs is of particular management relevance due to likely differences in movement patterns
of females accompanying calves.
Experience and Training
Tagging and biopsy techniques will only be carried out by trained and experienced researchers. All
personnel involved in these procedures will have been trained by experienced researchers familiar
with the equipment and methods used having participated in multiple field trips. This initial training
and knowledge transfer will be facilitated through the involvement of staff from Australian Antarctic
Division and Blue Planet. Level of experience does not necessarily affect the targeted whale – if a
person misfires, the tag or biopsy dart will either not fully implant and promptly fall out, or, will miss
the animal entirely. There is little additional risk to the animal.
Conclusion:
Through satellite tagging a small portion of migrating humpback whales we can gain a valuable
insight into how these animals utilise the waters of the WA coast. This data is not available through
alternate means and hence, through the use of a common, minimally invasive procedure, we can
gain valuable information to mitigate interactions between commercial fishing gear and migrating
whales. Any effect from satellite tagging is minimal compared to some of the effects of long-term
entanglement. Therefore, this data can result in a considerable net benefit to the welfare of this
whale population.
Rick Fletcher
Executive Director (Research)
/
/ 2014
APPROVED / NOT APPROVED