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Brood protection of wolf fish (Anarhichas lupus L.) eggs
Aquaculture, 65 (1987) 239-241 Elsevier Science Publishers B.V., Amsterdam -
239
Printed in The Netherlands
Brood Protection of Wolf Fish (Anarhichas lupus L.) Eggs EINAR RING0’ and HERMOD LORENTSEN’ ‘Institute of Fisheries, University of Tromss, P.O. Box 3083, Guleng, N-9001 Troms# (Norway) ‘Marine Biological Station, University of Tromsn, P.O. Box 2550, Ser Tromseya, N-9001 Troms0 (Norway) (Accepted 25 February 1987)
ABSTRACT Ringe, E. and Lorentsen, H., 1987. Brood protection of wolf fish (Anarhichas lupus L.) eggs. Aquaculture, 65: 239-241. The wolf fish (Anarhichas lupus L.) has considerable potential for aquaculture. This note describes brood protection by the fish as observed in the aquarium in Tromsa, Northern Norway.
Wolf fish (A. lupus) has considerable potential for aquaculture because of the excellent quality of its meat. The wolf fish is a bottom-living species which feeds on crabs, sea urchins, snails and molluscs. It is common in the Arctic Ocean, North Sea and around the coast of Greenland, Iceland and Great Britain. Some information is available about the biology of the species, and initial feeding by wolf fish fry has been described by Ring4 et al. (1987 ) . This note describes brood protection of wolf fish eggs in the sea-water aquarium in Tromsa, Northern Norway. Observations were made in 1982 and 1983, starting in June when fish showed signs of reproductive activity. Wolf fish are relatively easy to keep in captivity, provided that adequate hiding places are provided. For successful breeding, a pair must be kept apart from conspecifics; the introduction of a third wolf fish into the aquarium may result in fighting and serious injury. According to Bigelow and Schroeder (1953) there is no reason to suppose that wolf fish attack other fishes in their normal way of life. Field observations of wolf fish have shown that the fish spawn in holes under and between boulders in late August (Keats et al., 1985). In the TromsQ Sea Aquarium they spawned in July, and eggs (diameter c. 5.5 mm 1 were deposited in a clump on the bottom of the aquarium. The parental roles of the male and female wolf fish were very different, with the male alone protecting the brood. This is in accordance with the observations of Keats et al.
0044-0466/87/$03.50
0 1987 Elsevier Science Publishers B.V.
240
Fig. 1. Newly hatched wolf fish fry (from Ring4 et al., 1987).
(1985). The female appeared to be exhausted after spawning and lay and fasted on the bottom of the aquarium for at least one week. Ostvedt (1963) reported that egg masses of spotted catfish ( Anarhich minor Olafsen ) were loose, but we observed that the eggs of A. lupus were tightly clumped together. While protecting the brood throughout July-November, the male did not eat. The egg mass was turned more or less continuously by the male slowly moving his tail. The fry hatched as feeding larvae, with about 10% of the yolk remaining, after approximately 1000 degree-days of incubation (Fig. 1) . This is in accordance with the observations of Ringer et al. (1987) under conditions of artificial brood protection. There may be several reasons for brood protection, such as promotion of natural growth and development, or protection against predation. We observed that the male wolf fish enclosed the egg mass in a layer of skin mucus, and it is generally supposed that the skin mucus of fish is important in natural defence against parasites and pathogenic micro-organisms (Fletcher, 1978; Ingram, 1980). ACKNOWLEDGEMENTS
We thank R. Barret
for his help during the preparation
of this paper.
REFERENCES Bigelow, H.B. and Schroeder, W.C., 1953. The wolf fishes. Family Anarhichidae. Fish. Bull., 53: 502-508.
241 Fletcher, T.C., 1978. Defence mechanisms in fish. In: D.C. Malins and J.R. Sargent (Editors), Biochemical and Biophysical Perspectives in Marine Biology, Vol. IV. Academic Press, London, pp. 199-222 Ingram, G.A., 1960. Substances involved in the natural resistance of fish to infection. A review. J. Fish Biol., 16: 23-60. Keats, D.W., South, G.R. and Steele, D.H., 1985. Reproduction and egg guarding by Atlantic wolffish (Anarhichas lupus: Anarhichidae) and ocean pout (Macrozoarces americanus: Zoarcidae) in Newfoundland waters. Can. J. Zool., 63: 2565-2566. Ringe, E., Olsen, R.E. and Bee, B., 1987. Initial feeding of wolf fish (Anarhichas lupus L. 1 fry. Aquaculture, 62: 33-43. 0stvedt, O.J., 1963. On the life history of spotted catfish (Anarhichas minor Olafsen) . Rep. Norw. Fish. Mar. Invest., 13: 54-72.
239
Printed in The Netherlands
Brood Protection of Wolf Fish (Anarhichas lupus L.) Eggs EINAR RING0’ and HERMOD LORENTSEN’ ‘Institute of Fisheries, University of Tromss, P.O. Box 3083, Guleng, N-9001 Troms# (Norway) ‘Marine Biological Station, University of Tromsn, P.O. Box 2550, Ser Tromseya, N-9001 Troms0 (Norway) (Accepted 25 February 1987)
ABSTRACT Ringe, E. and Lorentsen, H., 1987. Brood protection of wolf fish (Anarhichas lupus L.) eggs. Aquaculture, 65: 239-241. The wolf fish (Anarhichas lupus L.) has considerable potential for aquaculture. This note describes brood protection by the fish as observed in the aquarium in Tromsa, Northern Norway.
Wolf fish (A. lupus) has considerable potential for aquaculture because of the excellent quality of its meat. The wolf fish is a bottom-living species which feeds on crabs, sea urchins, snails and molluscs. It is common in the Arctic Ocean, North Sea and around the coast of Greenland, Iceland and Great Britain. Some information is available about the biology of the species, and initial feeding by wolf fish fry has been described by Ring4 et al. (1987 ) . This note describes brood protection of wolf fish eggs in the sea-water aquarium in Tromsa, Northern Norway. Observations were made in 1982 and 1983, starting in June when fish showed signs of reproductive activity. Wolf fish are relatively easy to keep in captivity, provided that adequate hiding places are provided. For successful breeding, a pair must be kept apart from conspecifics; the introduction of a third wolf fish into the aquarium may result in fighting and serious injury. According to Bigelow and Schroeder (1953) there is no reason to suppose that wolf fish attack other fishes in their normal way of life. Field observations of wolf fish have shown that the fish spawn in holes under and between boulders in late August (Keats et al., 1985). In the TromsQ Sea Aquarium they spawned in July, and eggs (diameter c. 5.5 mm 1 were deposited in a clump on the bottom of the aquarium. The parental roles of the male and female wolf fish were very different, with the male alone protecting the brood. This is in accordance with the observations of Keats et al.
0044-0466/87/$03.50
0 1987 Elsevier Science Publishers B.V.
240
Fig. 1. Newly hatched wolf fish fry (from Ring4 et al., 1987).
(1985). The female appeared to be exhausted after spawning and lay and fasted on the bottom of the aquarium for at least one week. Ostvedt (1963) reported that egg masses of spotted catfish ( Anarhich minor Olafsen ) were loose, but we observed that the eggs of A. lupus were tightly clumped together. While protecting the brood throughout July-November, the male did not eat. The egg mass was turned more or less continuously by the male slowly moving his tail. The fry hatched as feeding larvae, with about 10% of the yolk remaining, after approximately 1000 degree-days of incubation (Fig. 1) . This is in accordance with the observations of Ringer et al. (1987) under conditions of artificial brood protection. There may be several reasons for brood protection, such as promotion of natural growth and development, or protection against predation. We observed that the male wolf fish enclosed the egg mass in a layer of skin mucus, and it is generally supposed that the skin mucus of fish is important in natural defence against parasites and pathogenic micro-organisms (Fletcher, 1978; Ingram, 1980). ACKNOWLEDGEMENTS
We thank R. Barret
for his help during the preparation
of this paper.
REFERENCES Bigelow, H.B. and Schroeder, W.C., 1953. The wolf fishes. Family Anarhichidae. Fish. Bull., 53: 502-508.
241 Fletcher, T.C., 1978. Defence mechanisms in fish. In: D.C. Malins and J.R. Sargent (Editors), Biochemical and Biophysical Perspectives in Marine Biology, Vol. IV. Academic Press, London, pp. 199-222 Ingram, G.A., 1960. Substances involved in the natural resistance of fish to infection. A review. J. Fish Biol., 16: 23-60. Keats, D.W., South, G.R. and Steele, D.H., 1985. Reproduction and egg guarding by Atlantic wolffish (Anarhichas lupus: Anarhichidae) and ocean pout (Macrozoarces americanus: Zoarcidae) in Newfoundland waters. Can. J. Zool., 63: 2565-2566. Ringe, E., Olsen, R.E. and Bee, B., 1987. Initial feeding of wolf fish (Anarhichas lupus L. 1 fry. Aquaculture, 62: 33-43. 0stvedt, O.J., 1963. On the life history of spotted catfish (Anarhichas minor Olafsen) . Rep. Norw. Fish. Mar. Invest., 13: 54-72.