692 



ADStr3Ct.— Fishing pressure on 

 deepwater oreosomatids has increased 

 recently in Australian and New Zea- 

 land waters, and yet little is known 

 about these fish. Genetic variation and 

 phylogenetic relationships among Aus- 

 tralian species was examined. Allozyme 

 variation at 26 loci was examined in 

 seven species: six from Australasia 

 (Allocyttus niger, black oreo; A. ver- 

 rucosus, warty oreo; Neocyttus rhom- 

 boidalis, spiky oreo; Oreosoma atlanti- 

 cum, oxeye oreo; Pseudocyttus macu- 

 latus, smooth oreo; and a new species 

 Neocyttus sp., rough oreo, infrequently 

 captured with the smooth oreo and 

 black oreo) and one from the North At- 

 lantic {N. helgae). Two phenetic trees 

 were constructed: an unweighted pair- 

 group method with arithmetic averag- 

 ing (UPGMA) tree derived from Nei's 

 unbiased genetic distances and a dis- 

 tance-Wagner tree derived from Rogers' 

 distances. A maximum parsimony cla- 

 distic analysis, with loci as characters 

 and alleles as unordered states, was 

 also performed. Outgroup species came 

 from three related families: Acanthur- 

 idae, Berycidae, and Zeidae. 



Mean heterozygosity per locus for the 

 seven oreo species was relatively high 

 for teleosts (11.8%), with O. atlanticum 

 having the lowest value (8.3%) and N. 

 sp. having the highest value (18.1%). 

 Oreosoma atlanticum was the most di- 

 vergent, with a mean genetic identity 

 (I) of 0.371. The two most closely re- 

 lated species — N. rhomboidalis and N. 

 helgae (1=0.973) — did not have any di- 

 agnostic allozyme loci, although the 

 muscle protein patterns, after Coo- 

 massie blue staining, were distinctive. 

 There was little evidence to support the 

 inclusion of A. niger and A. verrucosus 

 in the same genus; these two species 

 had a genetic identity of 0.695. Allo- 

 cyttus niger appeared to be more closely 

 related to members of the genus Neo- 

 cyttus than to A. verrucosus. Phenetic 

 analyses revealed only minor differences 

 in the Oreosomatidae grouping with re- 

 spect to the three outgroups, whereas cla- 

 distic analyses revealed the Zeidae as the 

 most closely related family. 



Genetic variation and phylogenetic 

 relationships of seven oreo species 

 (Teleostei, Oreosomatidae) inferred 

 from allozyme analysis 



Patricia S. Lowry 

 Nicholas G. Elliott* 

 Gordon K. Yearsley 

 Robert D. Ward 



CSIRO Division of Fisheries 



GPO Box 1538, Hobart. Tasmania 7001, Australia 



e-mail address Nick Elliott@ml csiro au 



Manuscript accepted 6 June 1996. 

 Fishery Bulletin 94:692-706 ( 1996) 



Oreos are laterally compressed, 

 deep-bodied fish with large heads 

 and large eyes. They are found in 

 deepwater (below 500 m) over the 

 continental slopes of most temper- 

 ate, and some tropical and subtropi- 

 cal, regions. They appear to be more 

 common in the Southern Hemi- 

 sphere, but this may reflect a greater 

 deepwater trawling effort in such re- 

 gions as New Zealand and Australia. 



The family Oreosomatidae (order 

 Zeiformes) contains four genera. In 

 a revision of oreos from the south- 

 ern oceans, James et al. (1988) re- 

 ported that, although the family is 

 well defined and recognizable, its 

 generic relationships are less clear: 

 the genera Allocyttus, Neocyttus, 

 and Oreosoma need redefining. The 

 fourth genus, Pseudocyttus, is well 

 defined and distinguishable. 



Oreos are among the most abun- 

 dant benthopelagic fishes on the 

 continental slope of southern Aus- 

 tralia, yet little is known of their 

 biology, stock structure, or phylog- 

 eny. In New Zealand waters, oreos 

 have been fished commercially since 

 the late 1970's. A peak catch of 

 26,500 metric tons (t) was taken in 

 1981-82; the fishery has since mod- 

 erated to around 19,000 t per year 

 (Lyle et al., 1992). The New Zealand 

 fishery comprises two main species: 



the smooth oreo (Pseudocyttus 

 maculatus Gilchrist, 1906) and the 

 black oreo (Allocyttus niger James 

 et al., 1988). In Australian waters 

 oreos have been caught largely as a 

 bycatch of the deepwater fisheries 

 for blue grenadier (Macruronus 

 novaezelandiae (Hector, 1871)) and 

 orange roughy (Hoplostethus atlan- 

 ticus Collett, 1889) and were gen- 

 erally discarded. However, recent 

 drastic reductions in orange roughy 

 catch limits, the development of 

 new deepwater fishing grounds off 

 southern Tasmania, and growing 

 market awareness have resulted in 

 increased targeting of species aggre- 

 gations and a rapid growth and re- 

 tention of Australian catches of 

 oreos (Lyle et al., 1992). The re- 

 tained catch of oreo from the south- 

 east fishery (the main deepwater 

 trawl fishery in Australia) was less 

 than 100 metric tons (t) per annum 

 before 1987, around 2,000 t in 1990 

 and 1991, over 3,000 t in 1992, and 

 over 1,000 t in 1993 and 1994 (Aus- 

 tralian Fisheries Management Au- 

 thority 1 ). Actual catches are prob- 



* Author to whom correspondence should be 

 sent. 



1 Australian Fisheries Management Author- 

 ity. 1995. Burns Centre, 28 National 

 Circuit, Forrest Act 2603, Australia. 

 Unpubl. data. 



