The North Atlantic Marine Mammal Commission

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NAMMCO 25

Stock Status

Stock assessment

NAMMCO has an ongoing programme to conduct assessments of fin whale stocks in the North Atlantic. The Scientific Committee of NAMMCO began this process in 1999, and to date has concentrated mainly on the East Greenland-Iceland stock (EGI) or Central stock (C) (see under North Atlantic Stocks), and fin whales around the Faroe Islands (NAMMCO 2000ab, 2001ab, 2004ab, 2006ab). An update for the northern part of the region was undertaken in 2006 in a joint workshop with the IWC (IWC 2007, NAMMCO 2007b) and continued in 2010, with new abundance data (NAMMCO 2011bc).

The first two assessments were based on the Hitter-Fitter procedure. The two next assessments used a two- then a four-substock model approach, while the last assessment in 2010 (NAMMCO 2011b,c) is based on using a RMP-based procedure (Revised Management Procedure or IWC-like procedure).

The main uncertainty concerning fin whales in the North Atlantic remains the stock structure, with a set of possible hypotheses (see under North Atlantic Stocks for details) ranging from one stock covering the whole North Atlantic to five or more separate stocks - fin whales in the Mediterranean representing a separate stock (NAMMCO 2007b).

Central or EGI stock

Besides recent abundance and trends in abundance estimates, the assessment of EGI fin whales is based on two sets of CPUE data (Catch Per Unit Effort), which provide information on trends in abundance over the 1901-1915 and 1962-1987 periods, i.e. before the series of NASS abundance surveys started.

Since 2003 (NAMMCO 2004a), the successive assessments of the EGI stock, although using different methodologies and lastely the new abundance estimate from the 2007 survey, have come to the same conclusion. The population has been increasing, although this increase is now likely ceased, and is approaching or at its initial, pre-harvest abundance (NAMMCO 2004ab, 2006ab, 2007bc, 2011bc), with over 20,000 whales.

The West Iceland management area (WI), from where catches were traditionnally taken, has had the highest rate of increase (10% between 1987 and 2001, NAMMCO 2007b; see also Figures under Current Abundance and Trends) and is currently above MSY level (Maximum Sustainable Yield).

Under very conservative assumptions about stock structure and the rate of population growth, it is very likely that the stock can maintain an annual harvest of about 150 whales. This result is based on the assumption that catches are confined to the West Iceland area, i.e. to the grounds from which fin whales have been traditionally taken. If catches were spread over a wider area than they were in the recent past, sustainable catches could probably be higher (NAMMCO 2004ab, 2006ab, 2007bc, 2011bc). In 2009, the IWC also reached the same conclusion (IWC 2010a).

The favourable status of North Atlantic fin whales is also reflected in the recent regional IUCN assessment for Europe where the species is not considered threatened (Temple and Terry 2007).

Faroes

Fin whales around the Faroe Islands are now considered part of the East Iceland-Faroe Islands stock area (see Figure under North Atlantic Stocks), but the stock relationships of these whales are unclear. Present summer abundance is relatively low in the area, and high catches were taken here in the past. If fin whales in this area comprise a separate stock, then they must be severely depleted (to 11% or less of initial numbers; NAMMCO 2001ab, 2004ab). However, if these fin whales are part of another, larger stock, then the level of depletion would not be so great. There is some indication that they may be, as a single fin whale tagged with a satellite-linked transmitter near the Faroe Islands, moved south to the Bay of Biscay, then returned north to an area off northwest Ireland, between August and November (NAMMCO 2003, Mikkelsen et al. 2007). Also, there is a continuous distribution of fin whales between the Faroe Islands and eastern Iceland, indicating that they may be linked to the East Greenland-Iceland stock. Stock delineation remains the greatest problem for the assessment of fin whales in this areas (NAMMCO 2004ab), and little progress has been made in this field.

West Greenland stock

NAMMCO has not assessed the stock of fin whales off West Greenland, because of the need for newer abundance estimate and the uncertain stock affiliations of fin whales in this area. New estimates have now been obtained and endorsed and an assessment could be conducted. An annual aboriginal quota of 19 whales is considered sustainable by the IWC (latest IWC 2009a).

East or North and West Norway stock

Until now, it has not yet been possible to conduct an assessment for this area. However, given the rather low abundance estimates and the high historical harvest in the area, it can be expected that the stock will be found to be depleted. With new information (for example, abundance estimates, catch statistics, stock structure, etc.) now obtained for the areas, future assessment efforts can be directed towards this area.

Outlook

Fin whales were a primary target for modern whaling. They were heavily reduced over their whole distribution range, although less so in the North Atlantic than in the North Pacific and Southern Hemisphere. The 70% overall population decline in the period 1929-2007 was mostly attributable to the major decline in the Southern Hemisphere (Reilly et al. 2008).

In the North Atlantic recent surveys and trend analyses show clear evidence of recovery. The population is now likely close to or larger than before the onset of modern whaling in the 1880s, numbering over 50,000 fin whales (NAMMCO 2011ac, Reilly et al. 2008). See under Current Abundance & Trends for details. The favourable status of North Atlantic fin whales is also reflected in the recent regional IUCN assessment for Europe where the species is not considered threatened (Temple and Terry 2007).

For the Central North Atlantic stock (C/EGI, East Greenland + West Iceland management areas), recent surveys and modelling suggest that the population has been increasing, although this increase is now likely ceased, and that the population is approaching or at its initial, pre-harvest abundance (NAMMCO 2004ab, 2006ab, 2007bc, 2011bc), with over 20,000 whales.

The West Iceland management area (WI), from where catches were traditionally taken, has had the highest rate of increase (NAMMCO 2006ac, 2007bc; see also Figs 2 and 3 under Current Abundance and Trends). Although using different modelling approaches, the assessments NAMMCO has conducted since 2003 (2004ab, 2006ab, 2007bc, 2011bc) all indicate that catches of about 150 whales taken from this area were sustainable.

The status of fin whales in other parts of the North Atlantic has yet not been fully assessed.

Status according to other international organisations

International Whaling Commission (IWC)

In its 'Status of Whales', the IWC states "Assessments of the population status [of fin whales] in the central North Atlantic and off West Greenland have shown populations there to be in a healthy state".

Using a different approach to NAMMCO, the IWC also concluded (IWC 2010a), that catches of about 150 whales taken from the West Iceland management area were sustainable.

International Union for Conservation of Nature (IUCN)

The fin whale is classified as Endangered ('Facing a very high risk of extinction in the wild') on the IUCN Red List 2009 following the last assessment carried out in 2008 (Reilly et al. 2008).

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

The fin whale is listed on CITES Appendix I: 'Species threatened with extinction'. For information: Iceland, Norway and Japan, which hold reservations against this listing, are not bound by it.

Comments from NAMMCO on IUCN and CITES classification for the fin whale

Although IUCN and CITES assess many different species at the population or stock level, they do not do so for the fin whale. The fin whale is treated and listed as a single mega-population, grouping the three recognized populations of the North Atlantic, the Southern Hemisphere and the North Pacific.

NAMMCO strongly questions the scientific appropriateness of such ‘species’ listings, when the conservation status of different populations and stocks may be very different, as is the case for fin whales (latest NAMMCO 2010c). Indeed, the recent regional IUCN assessment for Europe does not consider the North Atlantic fin whales as threatened (Temple and Terry 2007).

Pooling different populations together under a single listing can be misleading as the stocks are by definition reproductively isolated and may have very different conservation histories. This is particularly dangerous when the populations pooled together are very different in size, as is the case for fin whales where the Southern Ocean population was much larger than the others.

In its 'Status of Whales', the IWC express the same opinion, stating "Although often people request information on status at the species level, biologically it is more sensible to consider status at the population level (although determining stock structure, particularly for populations where the breeding grounds are unknown, is difficult). A perfect example of why this is the case is the gray whale; there is one healthy population (and thus the species is not endangered) but also one critically endangered population that therefore requires immediate conservation action."

In the case of the fin whale, the Southern Hemisphere population represented nearly 90% of the world fin whale population at the onset of whaling, as can be seen from the IUCN estimated population trajectory 1920-2007 (Figure below). In its 2008 assessment the IUCN itself states, "Most of the global decline over the last three generations is attributable to the major decline in the Southern Hemisphere. The North Atlantic sub-population may have increased, while the trend in the North Pacific sub-population is uncertain" (Reilly et al. 2008).

IUCN fin pop trajec 1920 20070001

Estimated population trajectory of fin whales, 1920-2007, from Figure 1 of the 2008 IUCN report.

Regarding the IUCN listing, NAMMCO concluded in 2009 (NAMMCO 2010c) that as long as the IUCN continues its practice of pooling all fin whale stocks into single assessments, the outcome will be completely dominated by the heavily depleted Southern Hemisphere stocks(s) and North Atlantic fin whales will be classified as endangered even if the IUCN assessment clearly shows that they would qualify for a “least concern” listing if evaluated on an individual basis.

Regarding the CITES listing, NAMMCO concluded in 2006 (NAMMCO 2007a,c) that “on the basis of biological information including population distribution, abundance and stock structure, with reference to CITES criteria A, B and C, the fin whale population in the region of the Central North Atlantic (the EGI stock) did not meet any of the biological criteria for listing under CITES Appendix I (threatened with extinction)”.