Study of the growth of southern black and white monkfish stocks

Abstract

P. 1997. Study of the growth of southern black and white monkfish stocks. -ICES Journal of Marine Science, 54: 866-874.Growth parameters for black and white monkfish from ICES southern stocks, ICES Divisions VIIIc and IXa (Spanish and Portugese waters) were estimated from age readings of the first ray of the dorsal fin (illicia) sections and fitting the von Bertalanffy growth model. Black monkfish growth parameters were obtained by sex and for sexes combined, from 336 illicia, between 1989 and 1993. The birthdate was assumed to be 1 January and back-calculation procedures were applied to infer the fish length at that time. Growth patterns differed by sex, and females attain a greater body length. The growth parameters were also estimated for combined sexes from the overall sample, and the sex-ratio of 1.3:1 (males vs. females) was considered to be representative of the exploited population. The growth parameters were: L`=101.69 cm, k=0.08 year 1 and t 0 = 0.2 year. The white monkfish growth parameters were estimated for sexes combined from age reading of 165 illicia from fish caught in 1990 and 1993 in Spanish waters. The southern white monkfish grows faster and attains a greater body length than the southern black monkfish. The growth parameters were: L`=121.54 cm, k=0.102 year 1 and t 0 =0.032 year for the white monkfish.1997 International Council for the Exploration of the Sea

Anglerfish (Lophius spp) in Nordic waters

“…Wright et al (2002) used microincrements in the lapilli otoliths of L. piscatorius (see Hislop et al 2001) to verify age estimates of specimens <27 cm TL. These were found to be either 0-or 1-group, in contrast to estimates of small size at age by Dupouy et al (1984) and Duarte et al (1997).These differences may have been caused by earlier misinterpretation of the time of first formation of the translucent zone, which appears in autumn in the illicium of most 0-group individuals, but not in the sagittal otoliths.…”

“…Illicium ageing methods developed at these workshops have been adopted in most growth studies pertaining to southern European anglerfish stocks (Anon. 2001, Duarte et al 1994, Duarte et al 1997, Landa & Pereda 1997, Landa et al 1998, Landa et al 2001c, Quincoces et al 1998, Quincoces et al 1998. In recent years Icelandic researchers have also undertaken efforts at age reading from illicia (see (2004)).…”

“…The age reading was done by a scientist from the age reading department of the Marine Research Institute (MRI) in Reykjavik; an experienced reader of other demersal species (otolith) but with no prior experience of anglerfish nor illicia. The basic knowledge on the illica age reading of anglerfish was obtained from various litterature on the subject (Peronnet et al 1992, Duarte et al 1997 and also from the Norwegian scientist J E Dyb through personal communication, lending of photo-samples as well as his thesis on an anglerfish stock off the Norwegian coast, at the University of Bergen, 2003. Furthermore, Dyb´s approach and interpretation in age reading as well as those of others have been thoroughly discussed during the annual meetings of the Nordic anglerfish studygroup of which the author of this article is a participating member.…”

A synthesis of the early life history of the anglerfish, Lophius piscatorius (Linnaeus, 1758) in northern British waters

“…This is in agreement with estimates of length at age of L. piscatorius in Greek waters (Tsimenidis and Ondrias, 1980) and the Irish Sea (Crozier, 1989), based on counts of presumed annual growth zones in the sagittal otoliths. Slower growth rates, based on the enumeration of annual zones in sectioned illicia, have been reported for the Bay of Biscay/Celtic Sea (Dupuoy et al, 1986) and Iberian waters (Duarte et al, 1997).…”

“…Specimens measuring up to 12 cm can be caught near the surface (this paper) and fish of 6-7 cm have been caught on the sea bed (Bowman, 1920;Duarte et al, 1997;Marine Laboratory Aberdeen, unpublished data). Evidently, factors other than the attainment of a threshold length determine when settlement takes place.…”