By Dr. Alexander Arkhipkin
Senior Fisheries Scientist
Illex stocks are prone to high variability in abundance, resulting in instability in its fishery and marketing. The years of 2004 and 2005 were characterized by rather poor abundances of Illex and were followed by three consecutive years (2006-2008) of high abundances. During the 2008 fishery, the Falkland Islands Fisheries Department (FIFD) expressed concerns about the status of Illex stocks in 2009 due to much slower growth rates and consequently reduced fecundity because of the colder than usual water temperatures during the feeding season in February-May. Together with the possibility of spawning being delayed until August 2008, the decrease in fecundity might lead to quite a significant drop in recruitment abundance for 2009. Unfortunately, the forecast about the Illex abundance for 2009 appeared to be true, and the Illex fishing season of 2009 was virtually non-existent, being the worst in the history of the Falkland fishery.
After the lowest abundance year of 2009 it was almost impossible to expect the complete recovery of the stock in 2010. It is known that before their seasonal migrations to Falkland waters, Illex moves from their spawning/nursery grounds located off southern Brazil, Uruguay and northern Argentina through the High Seas region. Therefore, the abundance of the South Patagonian Stock at 45-47ºS in January-February may be a good potential indicator of the state of the fishery later in March-April on the Patagonian Shelf.
Results of the High Seas fishery in 2010 did not result in much optimism as to the likely performance of the Illex fishery over the remainder of the season in Falkland zones. Trawlers started reporting their catches from the first week of January, having 14-15 t per day of the summer-autumn spawning squid. Catches remained quite low until the end of the month. The proportion of immature SPS Illex gradually increased until the end of January. Compared to previous seasons, the SPS squid showed a low abundance with average monthly CPUE being only 12.7 t per day. Nevertheless, there might still be a chance for the SPS to appear on the High Seas in February. Up to 20 trawlers and 6 jiggers reported their catches to the FIFD on the High Seas in February. Average daily CPUEs varied from 11 to 18 t in the first week of the month (maximum 30 t per day), and then decreased to 4-5 t per day during the second and third weeks. These catches were about only a third of that usually observed in a normal Illex year. Migrations of squid further south were further aggravated by cold environmental conditions of the Patagonian Shelf, where the sea surface temperatures had negative anomalies up to 2.5°C.
Nevertheless, a substantial jigging fleet applied for Falkland licenses to fish for Illex in a season that starts on 15th February. In the last four days of February, five jiggers fished for Illex in the northern part of Falkland Islands Interim Conservation and Management Zone (FICZ), but had low catches ranging from zero to 5.3 t per night (mean=1.7 t). Twenty four jiggers joined the fishery in the beginning of March, and their number gradually increased to 74 vessels by the 26th of March. During the first week of the month the catches were reasonable ranging from 10 to 19 t per night. Then they decreased to only 2.7-7.5 t per night. The mean monthly CPUE in March was only 5.9 t per night. In April, negative SST anomalies were observed in Falkland waters. However, they were not as strong as in previous months with SST being about 1°C below the mean annual norm of 1971-2000. The whole jigging fleet worked mainly in the northern part of FICZ during the first two weeks of the month. Daily CPUEs ranged only between 2 and 3.5 t per night. During the third week, CPUEs declined to 0.5-1 t per night, and the vessels started to leave the Falkland waters. The last three jiggers left Falklan Conservation Zones on 27th April, all having zero catches in the previous night. In April, squid in jigger catches were relatively large in respect to the same period of 1999-2008 with modal lengths ranging from 29 to 30.5 cm ML.
The Illex season of 2010 brought a total catch of 12,105 t this is the fourth lowest catch of this squid since the beginning of the Falkland fishery in 1987. All jiggers issued with B-licenses are due significant reimbursement of fees.
Overall, the commercial situation in the Illex fishery in 2010 was quite similar to that observed in 2002, when the South Patagonian Stock of Illexhad low abundance and their migration to the southern parts of their species range on the Patagonian Shelf was restricted by unfavourably low water temperatures.
The recruitment abundance for the next year season (2011) will depend on several factors. Larger sizes of squid observed in 2010 would translate into higher fecundities that may result in a partial recovery of the South Patagonian Stock next year (as it happened in 2006 after the poor year of 2005). Exploitation rate of the standing and spawning biomass will determine the abundance of spawners that will reach the spawning grounds in July-August 2010. Another factor that might affect the recruitment abundance are environmental conditions in the spawning grounds in August-September, with positive SST anomalies contributing to higher survival of larvae and juveniles for the 2011 fishery.
Illex is one of the straddling stocks in the Southern Atlantic that during its ontogenetic migrations appears in the Exclusive Economic Zones of Brazil, Uruguay and Argentina, as well as in Falkland Conservation Zones and on the High Seas at 42ºS and 45-47 ºS beyond the Argentinean EEZ. Effective management and conservation of this important resource is therefore only possible by some kind of regional fisheries management organisation (RFMO) that should include all countries whose fleets are participating in exploitation of Illex stocks. So far, such an organisation does not exist and this makes the squid stocks vulnerable to over-exploitation especially in years of their low abundance.
In the past, Illex stocks were monitored during their migrations in Argentinean and Falkland waters by the bilateral Argentine-UK South Atlantic Fisheries Commission (SAFC). The SAFC organised joint research surveys of Illex recruitment before the fishing season, supervised the exchange of commercial and biological information between the respective fisheries authorities in and subsequent joint estimation of the spawning stock biomass (SSB). If the SSB was calculated as falling below the threshold limit of 40,000 t for the Southwest Atlantic, the SAFC recommended early closure of theIllex fisheries in Argentina and the Falkland Islands with early closures being implemented in a number of years. The SAFC also organised joint meetings between Argentinean and UK/Falkland Islands scientists to exchange their opinions on the fisheries. Unfortunately, since 2005 the SAFC has been largely moribund as the Argentine Government reduced co-operation, declining to continue the routine joint meeting process and suspending joint scientific activities. This has undoubtedly increased the vulnerability of Illex squid stocks.
Illex squid are a major component of the commercial fisheries of the Southwest Atlantic including Argentine and Falkland fishing zones and the high seas. More than that and despite their seasonal abundance and variability they are one of the most significant components of the Southwest Atlantic ecosystem. This is one of the few remaining areas of the world’s oceans which could really benefit from a robust and effective regional fisheries management organisation. The revival of the SAFC could play a vital role in that together with dealing with bilateral fisheries issues.