The possible adaptive advantages of terrestrial egg deposition in some fluvial diadromous galaxiid fishes (Teleostei: Galaxiidae)

Several diadromous New Zealand and Australian species of Galaxias are now known, or suspected, to deposit their eggs amongst riparian vegetation or substrates either supratidally in estuaries or in forested streams in locations that are only temporarily submerged by elevated water levels. The eggs develop in a humid atmosphere and hatch when the egg deposition sites are resubmerged; a significant role for agitation in stimulating hatching seeming likely. There are risks from the eggs becoming dehydrated, and also from a failure by water to resubmerge the eggs before they have exhausted their energy resources. Hatching is triggered by elevated flows, perhaps being an outcome of agitation of the eggs. Elevated flows may also increase the rate of downstream transport of the larvae, facilitating survival during dispersal to sea from spawning sites in streams that may be long distances inland. Hatching during flood events may favour survival of the larvae because turbid flows may provide ‘cover’ for the larvae as they emigrate to sea. Risks from egg predation by aquatic predators may be replaced by risks from terrestrial predators.

[1]  A. Kliskey,et al.  Spatial Modeling and Habitat Quantification for Two Diadromous Fish in New Zealand Streams: A GIS-Based Approach with Application for Conservation Management , 2005, Environmental management.

[2]  K. Iwata,et al.  Intra-specific variations of egg size, clutch size and larval survival relatedto maternal size in amphidromous Rhinogobius goby , 2005, Environmental Biology of Fishes.

[3]  G. Scott,et al.  Reproductive behavior of the Atlantic silverside, Menidia menidia (Pisces, Atherinidae) , 1981, Environmental Biology of Fishes.

[4]  E. Balon.  Additions and amendments to the classification of reproductive styles in fishes , 1981, Environmental Biology of Fishes.

[5]  R. Death,et al.  Spawning site selection, egg development, and larval drift of Galaxias postvectis and G. fasciatus in a New Zealand stream , 2003 .

[6]  D. Rowe,et al.  Use of in‐stream cover types by adult banded kokopu (Galaxias fasciatus) in first‐order North Island, New Zealand, streams , 2003 .

[7]  Sjaan C. Charteris.  Spawning, egg development and recruitment of diadromous galaxiids in Taranaki, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University , 2002 .

[8]  R. Allibone,et al.  Timing and habitat of koaro (Galaxias brevipinnis) spawning in streams draining MtTaranaki, New Zealand , 2000 .

[9]  K. Iguchi,et al.  Early starvation limits survival in amphidromous fishes , 1999 .

[10]  K. Martin,et al.  Metabolism during Delayed Hatching in Terrestrial Eggs of a Marine Fish, the Grunion Leuresthes tenuis , 1998, Physiological Zoology.

[11]  J. Koehn,et al.  Spawning of the broad‐finned Galaxias, Galaxias brevipinnis Günther (Pisces: Galaxiidae) in coastal streams of southeastern Australia , 1998 .

[12]  C. Townsend,et al.  Reproductive biology, species status and taxonomic relationships of four recently discovered galaxiid fishes in a New Zealand river. , 1997, Journal of fish biology.

[13]  R. McDowall,et al.  Emigrating larvae of koaro, Galaxias brevipinnis Günther (Teleostei: Galaxiidae), from the Otira River, New Zealand , 1995 .

[14]  C. Mitchell,et al.  Age at migration from the sea of juvenile Galaxias in New Zealand (Pisces: Galaxiidae) , 1994 .

[15]  C. Mitchell.  Deposition of Galaxias fasciatus eggs with Galaxias maculatus eggs at a tidal site , 1991 .

[16]  C. Mitchell.  Laboratory culture of Galaxias maculatus and potential applications , 1989 .

[17]  P. Humphries.  Variation in the Life History of Diadromous and Landlocked Populations of the Spotted Galaxias, Galaxias truttaceus Valenciennes, in Tasmania , 1989 .

[18]  D. Conover,et al.  Adaptive significance of intertidal egg deposition in the Atlantic silverside Menidia menidia , 1987 .

[19]  L. Dimichele,et al.  Spawning Site Utilization in a Delaware Population of Fundulus heteroclitus (Pisces: Cyprinodontidae) , 1983 .

[20]  C. Mitchell,et al.  Spawning of Galaxias fasciatus Gray (Salmoniformes: Galaxiidae) , 1982 .

[21]  P. L. Cadwallader.  Breeding biology of a non-diadromous galaxiid, Galaxias vulgaris Stokell, in a New Zealand river , 1976 .

[22]  E. Balon,et al.  Reproductive Guilds of Fishes: A Proposal and Definition , 1975 .

[23]  G. Eldon,et al.  Downstream movement of fry of galaxias fasciatus gray (note) , 1975 .

[24]  R. McDowall.  The species problem in freshwater fishes and the taxonomy of diadromous and lacustrine populations of Galaxias maculatus (Jenyns) , 1972 .

[25]  D. Pollard.  The biology of a landlocked form of the normally catadromous salmoniform fish Galaxias maculatus (Jenyns). I. Life cycle and origin , 1971 .

[26]  Vivienne Benzie.  Stages in the normal development of Galaxias maculatus attenuatus (Jenyns) , 1968 .

[27]  V. Loosanoff.  The Spawning run of the pacific surf smelt, Hypomesus pretiosus [Girard] , 1938 .