The use of beaks as tools for biomass estimation in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

Jackson, George D.

doi:10.1007/bf00236118

Cited by 32 publications

(22 citation statements)

References 11 publications

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“…As Jackson (1995) demonstrated, this is not the case for all squid species. However, since beaks of T. eblanae are difficult to distinguish from Illex coindetii beaks (Clarke 1986) the utility is actually limited in this case.…”

Section: Discussionmentioning

confidence: 92%

Research cruise data on the biology of the lesser flying squid,Todaropsis eblanae, in the North Sea

Zumholz

Piatkowski

2005

Aquat. Living Resour.

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-A total of 324 specimens of the ommastrephid squid Todaropsis eblanae, collected from bottom trawl surveys in the North Sea was examined. Information on seasonal length frequency distributions and relationships of beak size to mantle length and wet body mass from the northernmost distribution of the species is supplied. The overall male: female ratio was 1: 0.78. Maturing males and females were found in winter and summer, while fully mature animals were observed only in summer. Sexual maturity in females occurred in bigger sizes than in males. Specimens were caught in water depths between 56 and 170 m throughout the whole investigated area except from the German Bight. This paper presents the first biological data on T. eblanae in the North Sea derived from scientific surveys.Key words: Todaropsis eblanae / Cephalopoda / Ommastrephidae / North Sea / reproductive biology / beak / lower rostral length Résumé -Données de campagnes océanographiques sur la biologie du calmar Todaropsis eblanae en mer du Nord. Pour cette étude, 324 calmars Ommastraephidés de l'espèce Todaropsis eblanae récoltés durant des campagnes scientifiques de chalutage de fond en mer du Nord ont été analysés. Les fréquences de taille, relations entre la taille du bec et celle du manteau et les poids frais, décrits ici concernent la partie la plus nordique de l'aire de répartition de cette espèce. Globalement, le sex ratio est de 78 femelles pour 100 mâles. Des mâles et des femelles en cours de maturation sexuelle ont été trouvés en été comme en hiver alors que les animaux à maturité complète n'ont été observés qu'en été. La maturité sexuelle est atteinte à une taille plus grande chez les femelles que chez les mâles. Les captures de ce calmar ont eu lieu par des profondeurs de 56 à 170 m et dans toute la zone prospectée par les campagnes à l'exception du German Bight. Cet article présente les premières données biologiques concernant T. eblanae en mer du Nord obtenues à partir de campagnes scientifiques.

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Section: Discussionmentioning

confidence: 92%

Research cruise data on the biology of the lesser flying squid,Todaropsis eblanae, in the North Sea

Zumholz

Piatkowski

2005

Aquat. Living Resour.

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“…Standard length and biomass of fish species were calculated from the conversion of otolith length (mm) using allometric equations (Adams & Klages 1987, Williams & McEldowney 1990, Cherel et al 1997, Olsson & North 1997 for the majority of species. The conversion of lower rostral length to mantle length and squid body mass was achieved using allometric equations from Clarke (1986), Rodhouse et al (1990) and Jackson (1995). In reconstructing the estimated fish biomass consumed by fur seals from scats, each otolith was considered to represent 1 fish, as there is little chance of all fish and therefore otoliths consumed by the fur seal being present in a particular scat.…”

Section: Methodsmentioning

confidence: 99%

Antarctic fur seals foraging in the Polar Frontal Zone: inter-annual shifts in diet as shown from fecal and fatty acid analyses

Lea¹,

Cherel²,

Guinet³

et al. 2002

Mar. Ecol. Prog. Ser.

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We studied the dietary preferences of Antarctic fur seals Arctocephalus gazella from Cap Noir, Îles Kerguelen, foraging in the Antarctic Polar Frontal Zone (PFZ) in February of 1998February of , 1999February of and 2000. Scats were collected and analyzed for remaining prey hard parts in each of the 3 years, and in 1999 and 2000, the fatty acid (FA) composition of fur seal milk samples was also examined for longerterm dietary preferences. Scat analyses revealed that seals foraged primarily on fish and some squid in all 3 years with 25 species of fish being taken during the study. Myctophid fish accounted for an average of 94% by number of all fish consumed with 3 species, Gymnoscopelus nicholsi, G. piabilis and Electrona subaspera, forming the core diet. Inter-annual differences in dietary species composition were apparent, however, with the presence of the mackerel icefish Champsocephalus gunnari in 1998 and the myctophid Protomyctophum tenisoni in 1999 accounting primarily for the differences observed between years. While reconstituted prey biomass per scat was similar between years, scats from 1998 represented less energy per gram than those from 1999 and 2000. This study highlights the usefulness of using FA signature analysis to confirm longer-term shifts in dietary intake of fur seals using milk samples. Polyunsaturated fatty acids (PUFAs) were significantly more prevalent in the 1999 milk samples, which were also lower in overall lipid content (43% vs 53%). G. nicholsi, a particularly oily fish, occurred in higher proportions in the diet in 2000, perhaps explaining the higher incidence of monounsaturated fatty acids (MUFAs) in this year and the generally higher lipid levels present in milk samples. The inter-annual variation in the diet of Antarctic fur seals confirmed by these 2 techniques lends support to the hypothesis that previously identified variations in oceanographic conditions surrounding Îles Kerguelen in 1998, 1999 and 2000 affect the availability of fur seal prey resources.

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“…Length of uneroded or slightly eroded otoliths (OL) and dentary bones (ML for mandible length) of fish, lower rostral length (LRL) of squid beaks, lower hood length (LHL) of octopus beaks, and eye diameter or total length of crustaceans were measured with a vernier caliper or using an ocular scale in a binocular microscope. Fish standard length (SL), cephalopod dorsal mantle length (DML), crustacean total length and prey body masses (M) were calculated using regression equations (Clarke 1986, Adams & Klages 1987, Rodhouse & Yeatman 1990, Williams & McEldowney 1990, Ridoux 1994, Jackson 1995. For the few species where no relationships were available, length and M were estimated using equations for closely related species or for species with a similar morphology.…”

Section: Methodsmentioning

confidence: 99%

Food and feeding ecology of the neritic-slope forager black-browed albatross and its relationships with commercial fisheries in Kerguelen waters

Cherel

Weimerskirch

Trouvé

2000

Mar. Ecol. Prog. Ser.

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The use of beaks as tools for biomass estimation in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

Cited by 32 publications

References 11 publications

Research cruise data on the biology of the lesser flying squid,Todaropsis eblanae, in the North Sea

Research cruise data on the biology of the lesser flying squid,Todaropsis eblanae, in the North Sea

Antarctic fur seals foraging in the Polar Frontal Zone: inter-annual shifts in diet as shown from fecal and fatty acid analyses

Food and feeding ecology of the neritic-slope forager black-browed albatross and its relationships with commercial fisheries in Kerguelen waters

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