Aukin útbreiðsla skötusels við Íslands
Jón Sólmundsson, Einar Jónsson og Höskuldur Björnsson
Bls: 13–20 1. hefti 75. árg. 2007
Mikið hefur verið fjallað um hlýnun lofts og sjávar og hugsanleg áhrif þeirra breytinga á lífverur. Breytingar á sjávarhita þurfa ekki að vera miklar til að þeirra gæti í lífríkinu, því hver tegund eða stofn hefur sinn kjörhita og hitaþol. Algengustu fisktegundir hér við land eru líklegar til að mæta auknum sjávarhita með breyttri útbreiðslu, því þær geta synt langar leiðir milli svæða og berast auk þess með straumum sem egg og lirfur. Ein slík tegund er skötuselur (Lophius piscatorius) (1. mynd) sem virðist hafa stækkað búsvæði sitt hér við land samfara hækkandi sjávarhita.
Recent changes in the distribution of anglerfish in Icelandic waters
Anglerfish (Lophius piscatorius) is distributed in the eastern Atlantic Ocean from Gibraltar north to Iceland and North Norway. During the last decades, anglerfish in Icelandic waters has been most abundant in the warm waters in the south and southwest while it has been rare north and east of the country. This study describes recent changes in the spatial distribution and abundance of anglerfish in Icelandic waters, based mostly on data collected from the Icelandic groundfish survey in March that has been conducted annually since 1985. The stock size of anglerfish appears to have been increasing dramatically since 1998 and the species has been extending its spatial distribution along the continental shelf west off Iceland all the way to the areas northwest and north of Iceland. North Icelandic waters may, however, in some years be hazardous for this species due to harsh winter conditions. According to the Icelandic groundfish survey, anglerfish is rarely found in waters where bottom temperature is below 5°C. The changes in the distribution of anglerfish and increased stock size have co-occurred with rising water temperatures, and the latter are likely to have expanded suitable grounds for the species. These environmental changes may especially have benefited juveniles, since recruitment was hardly observed before year-class 1998 but since then several large year-classes have been observed. It is possible that a part of the stock of anglerfish in Icelandic waters originates from distant areas, either due to larval drift or active migration of larger fish. Migrations from the Shetland and Faroe Islands to the continental shelf south of Iceland have recently been confirmed by tagging experiments but the magnitude of the migration is not known. However, it is likely that since 1998 local recruitment contributes more to the stock than possible migrations from other areas.