Research Plan 2017

Research plan for 2017

The main aims for the project in 2017 are:

1. Obtaining behavioral data on depredating sperm whales as surface observations and acoustic recordings. Sperm whales use echolocation and analysis of recordings will provide information on how they used echolocation during depredation. In June, an attempt will be made to document this behavior also with an underwater camera.
2. Identifying sperm whale individuals interacting with the longlines
3. Tracking of individual sperm whales between the depredation events to get an idea how important this type of feeding is for the whales
4. Collect systematic records of depredation events (including number of individuals involved and estimates of catch loss) through cooperation with the fish landing sites
5. Further develop cooperation with the fishermen, who will be key partners in further development of the project, including mitigation issues
6. Combine existing information from marine research institute and fisheries organizations to get an overview of recent changes in the ecosystem which might explain the change in sperm whale distribution and why whales have started interacting with the longline fishery.

The pilot study in 2016 showed that an independent platform is essential for obtaining behavioral and identification data. In 2017 we will be using a motor sailing boat for field work as an extremely cost effective, safe, environmental friendly and efficient research platform.

Sperm whales will be searched for and detected both visually and acoustically around the area where the long line fishing fleet is operating. Our main target will be sperm whales observed approaching or associating with fishing vessels. Photo identification pictures, sound recordings, video footage of the behaviour at surface, dive times and length measurements (acoustic and photogrammetric) will be taken of the whales interacting with the longline.

Halibut fishing season starts 22/5 2017 and continues for approximately 2-3 weeks. After a pause the coastal fishery starts again in late July and continues for couple of weeks in August. During the first fishing season all effort will be put into getting more data on the depredation events, on the second season sperm whale individuals will be tracked after a depredation event for approximately 12 hours using passive acoustic techniques to provide detailed data on their behaviour - fine scale movements, association with scattering layers, feeding behaviour (assessed by detecting feeding vocalisations) and associations with other male sperm whales in the area. This approach will allow us to get better data on the depredation behaviour, but also put it in a wider context and also allow us to evaluate the importance of this behaviour for individual sperm whales and the local population as a whole.

Cooperation with fishery and mitigation techniques

The limited fishing area (around the 600 m depth contour) suggests that mitigation techniques based on avoidance (e.g. moving to somewhere else to fish if sperm whales are present) may not be effective here. The traditional fishery operates in groups of 4-5 boats working alongside each other in a limited area. Solutions could be based on decoys, use of aversive sounds or disruption of echolocation behavior. There is also an interest from several companies in finding technical solutions through alterations of the fishing gear. However, developing solutions for the depredation issue require a detailed understanding of sperm whale behavior. What is the “acoustic que” alerting the sperm whales to the presence of long lines and fish on them? Can anything be done to minimize these acoustic cues? How and at what depth do the whales take halibut from the longline?

Greenland Halibut caught by the coastal fishery is landed into five different locations. Cooperation with the landing sites will be essential for obtaining an estimate of the magnitude of depredation issue; frequency of depredation, number of whales/boat and estimates of catch loss. During the pilot study in 2016 reporting forms were given to the fishing vessels, however, as the fishing is very work intensive (with a crew of 1-3 persons) the fishermen often did not have time for or forgot about the reporting scheme. After an evaluation meeting, together with the fishermen in August 2016, it was agreed that it would be more efficient and accurate to cooperate through the landing sites.

Depredation – a sign of change in the ecosystem?

The problem of depredation by sperm whale and other toothed whales is growing around the world. This increase likely reflects both diminishing natural food supplies for the species as well as transmission of depredation behaviors between whales by social learning (Anon 2006)

Since 2010 the distribution of sperm whales has changed within our study area. The deep-water canyon has become of less importance as a feeding ground and sperm whales are found feeding in shallower waters. It is possible that this change, which has also brought the whales closer to the coastal longline fishing operation, explains why the whales have started to depredate from the longlines. It is also intriguing that the whale first identified carrying out this behavior in this area, had not been previously identified in these waters, also two other individuals interacting with the longlines have not been identified previously. They could potentially be individuals which have learned this behavior elsewhere, for example in Greenlandic waters where sperm whale depredation of Greenland halibut from long lines became a very substantial problem contributing to closure of that fishery (Dyb 2006). Sperm whales are social, adaptive animals capable of learning new behaviors culturally from others. This probably explains how depredation escalated so quickly into a significant problem, once it has started, in several other longline fisheries (Anon 2006, Arangio 2012).

For evaluation of underlying reasons for the change in sperm whale distribution within the study area, it is important to combine information from the marine research institute (sea temperature, plankton production, fish stocks etc) and from fisheries (catch statistics).

Future perspectives and the conservation aspects of the project

The situation in Norway (a fishery close to shore, operating within a limited and predictable fishing area with a high rate of depredation with which we have developed an excellent cooperative relationship) provides an ideal opportunity for studying the behaviour of sperm whales during depredation and for developing solutions. This will have relevance not only for the fishery in arctic Norway but also for those in other areas where depredation has escalated into a serious conflict between fisheries and sperm whales. Without well-informed interventions, the situation may lead to increasing conflicts between the sperm whales and fishermen. 

The project is one of only two studying male sperm whales in high latitudes and will contribute to our understanding of the behavioural ecology of sperm whales. In addition, the ongoing changes in the ecosystem, including changes in distribution pattern and foraging behaviour of sperm whales, allow for important scientific insights. Whenever there are major abrupt changes in an ecosystem, many aspects of its general dynamics that are normally hidden and difficult to observe and understand can suddenly become visible and there is an opportunity to learn something new. Improved understanding about a marine ecosystem and the factors that threaten to destabilize it makes it easier to develop effective and cost-effective conservation measures.