Anthropogenic activities which may affect fin whales can be divided in two main categories: habitat degradation and oceanographic changes. Knowledge about fin whale habitat use is limited and it is therefore difficult to assess the impact that they may represent for the species. At present their relative importance and scale have not been assessed and will vary greatly according to areas and time of the year.
A range of anthropogenic activities has the potential to degrade habitat important to fin whale survival, and may occur both when whales are present and absent. They include:
• entanglement (e.g. in marine debris, fishing gear, etc)
• physical injury and death from vessel collisions (service corridors and shipping lines)
• acoustic pollution with disturbance from low-frequency noise (vessel, seismic survey, military activities)
• changing water quality and pollution (e.g. runoff from agriculture, oil spills)
• prey depletion due to over-harvesting
• human harassment through whale watching programmes
Fin whales commonly lunge feed at or near the surface, which makes them vulnerable to ship strikes and entanglement. They are one of the more commonly recorded species of large whale reported as hit by vessels worldwide (Laist et al. 2001, Jensen and Silber 2003) and they are also occasionally caught in fishing gear as incidental catch or by-catch.
In the NAMMCO area, however, entanglement and ship strikes appear as a very minimal threat for fin whales. Over the period 2000–2009 (National Progress Reports, NAMMCO 2001–2010) only one by-catch and one strike have been reported for fin whales. One fin whale was entangled off West Greenland in ropes used in connection with crab traps (Anonym 2004), while the likely strike was caused by a ferry off Iceland (Ólafsdóttir pers. comm.). Reporting of large cetacean by-catch is only mandatory in Greenland and Iceland, but these events get much local attention, probably because they are very rare. The authorities become aware of most cases, if not all, through different channels, such as direct reports to museums and marine institutes or articles in newspapers. In the NAMMCO areas, fin whales are mainly distributed offshore, with little overlap with the main fishing areas, which likely explains the low risk of entanglement.
Fin whale from the air. Photo SFSC-NOAA
Noise from seismic exploration, military activities and shipping could affect fin whales directly or indirectly by interfering with their communication, but the effects are not known (IWC 2005). Since fin whales use low frequency sounds to call to females, human interruption through sound waves, such as military sonar and seismic surveys can disrupt the signal sent to the females. This can potentially interfere with mating by preventing mates from meeting and a consequential reduction in birth rates in populations (Croll et al. 2002).
The exact implications of climate change on oceanographic conditions and processes are unknown, as well as their subsequent implications for whales. Reduced productivity of some ecosystems and unpredictable weather events caused by altered ocean water temperatures, changing ocean currents, rising sea levels and reductions in sea ice are predicted as possible consequences of climate change.
Fin whale habitat areas might be affected directly through changes in food availability caused by decreased productivity and/or changed patterns in prey distribution and availability (e.g. Williams et al. 2013). Also, if ocean currents and water temperature influence whale migration, feeding, breeding, and calving site selection, any changes in these factors could render currently used habitat unsuitable.
Faroese stamps, Postverk Føroya 2001