HOUDE: BREGMACEROTIDAE 



301 



Bregmacerotidae. Bregmacerotids are small fishes, the largest 

 species, B. macclellandi, rarely exceeding 120 mm SL. They 

 have two dorsal fins, the first a single, elongate ray on the occiput. 

 The second dorsal fin and the anal fin are long with median rays 

 much reduced, giving the fins a divided appearance. The caudal 

 fin is separated from the dorsal and anal fins. Pelvic fins are 

 j ugular and consist of 5 (usually )-7 rays, the outer three elongate. 

 The olfactory nerves pass through a broad canal, wider than 

 that in Gadidae. The sacculus is very large. The swimbladder 

 does not contact the auditory capsules. There are a few pyloric 

 caeca. The vomer is toothed. A lateral line is present under 

 the second dorsal fin. Chin barbels are absent. 



Development 



Spawning. — Size at maturity is variable but generally <30 mm. 

 In one species, B. rarisquamosus. maturity is attained at < 1 5 

 mm (D'Ancona and Cavinato, 1965). Larvae occur in the tropics 

 and subtropics dunng all months, indicating protracted spawn- 

 ing, although seasonality is apparent for individual species in 

 some areas. 



£■^^5. — Eggs are presumed to be pelagic. Excepting a single re- 

 port, the fertilized eggs and embryos of Bregmaceros species 

 have not been described. Pertseva-Ostroumova and Rass (1973) 

 described fertilized eggs, attributable to B. atlaniicus. as pelagic 

 with smooth chorion, small perivitelline space and homoge- 

 neous yolk containing an oil globule. They reported the egg 

 diameter to be 1.1 mm and the oil globule diameter to be 0.20 

 mm. In my opinion, it is unlikely that Bregmaceros eggs are 

 that large because newly-hatched larvae are only 1.5 mm long. 

 Ahlstrom's'' unpublished notes give diameters of Z?. bathyniaster 

 eggs as 0.84-1.00 mm and indicate that a single oil globule is 

 present. 



Ten eggs with well-developed embryos that I examined, iden- 

 tified as B. bathymaster by E. H. Ahlstrom. collected in the 

 mouth of the Gulf of California^ ranged from 0.88-1 .00 mm in 

 diameter (.v = 0.94 mm) and had a single oil globule 0.22-0.28 

 mm in diameter (.v = 0.24 mm). The chorion was smooth, per- 

 ivitelline space narrow and yolk homogeneous. The oil globule 

 was situated in the posterior part of the yolk mass. Several small 

 melanophores were scattered on the head and dorsal side of the 

 embryo and on the ventral side of the tail. 



Larvae — The larvae are not unusual. Their general morphology 

 is similar to that of other gadiform larvae but bregmacerotids 

 are not likely to be confused with them or with larvae of other 

 tropical-subtropical fishes with which they occur. In bregma- 

 cerotids, metamorphosis is gradual and direct. 



Newly-hatched larvae are small, approximately 1.5 mm NL, 

 a fact often not appreciated when collecting nets with >333- 

 ^m meshes have been used. The smallest larvae usually have 



Table 83. Geographic Distribution Information and Some Meris- 



Tic Data of Bregmaceros Adults and Larvae > 8 mm SL. Numbers 



in parentheses are the most common counts for a species. For additional 



meristic data, see Fahay and Markle, this volume. 



' Ahlstrom, E. H. Personal Notes. "Gadiformes." Notes on file at 

 National Marine Fisheries Service, Southwest Fisheries Center, La Jolla, 

 California, USA. 



' The eggs, identified as B. bathymasler. were provided by Dr. H. G. 

 Moser, Southwest Fisheries Center, National Mannc Fisheries Service. 

 La Jolla, California. They were collected on 10 June 1957, Station 

 I45G.40, Cruise 5706-S, near the mouth of the Gulf of California. I 

 could not confirm that the eggs were those of Bregmaceros. although 

 embryo myomere numbers were in the reported range for B. bathy- 

 master. 



' CT = circumlropical; O = oceanic; N = nentic; WP = weslem Pacific; I = Indian; IP = Indo- 

 Pacific; WA = weslem Atlanlic; EP = eastern Pacific. 



not been described, although it is dunng that stage when specific 

 pigmentation is unique and identification easiest. Small speci- 

 mens (1.5-3.1 mm NL) of eight species are illustrated (Figs. 153 

 and 154). Larvae of 3.0-6.0 mm SL may be most difficult to 

 identify because pigment patterns are in transition and fin rays 

 have not developed sufliciently to be diagnostic. At lengths > 6.0 

 mm identification becomes easier, based on pigmentation char- 

 acteristics (Figs. 1 55 and I 56) and on complete (or nearly com- 

 plete) counts of median fin rays and myomeres. For larvae >10- 

 1 1 mm, diagnostic meristics usually are complete and illustra- 

 tions/descriptions in D'Ancona and Cavinato (1965) and Be- 

 lyanina (1974) usually will lead to correct identifications. Use 

 of information on larval pigmentation, meristics and size at 

 occipital ray development allow all described species to be iden- 

 tified. 



Occipital ray (Table 84).— The size at appearance of the single 

 occipital ray varies among species. It is the first fin ray to develop 

 in B. macclellandi and in B. Type A (Houde, 1981), appearing 

 when larvae are 2.0-2.5 mm in length. In all other species the 

 ray develops at lengths of 5.0-7.5 mm, usually at approximately 

 6.5 mm. The occipital ray ofB. macclellandi is long and delicate, 

 often extending to near the middle of the second dorsal fin in 

 specimens < 1 mm, but subsequently declining in relative length. 

 In other species, the occipital ray is shorter, never reaching the 

 second dorsal fin. 



Pigiyientation (Table 84) —'Larvae of the oceanic species B. 

 macclellandi and B. atlanticus are darkly pigmented. Larvae of 

 the neritic species are lightly pigmented. All have heavy internal 

 pigment over the visceral mass. The most distinctive pigment 

 is present on the smallest larvae (Figs. 153 and 154) and all 

 described species can be identified using pigmentation patterns 

 for larvae of 1.5-3.0 mm SL. The amounts of pigment, and 

 particularly the diagnostic melanophore patterns, tend to be lost 

 or reduced as larvae grow. External pigment tends to migrate 

 internally with growth, the tendency being most apparent in the 

 neritic Indo-Pacific species B. nectabanus. B. arabicus and B. 

 rarisquamosus. At the smallest lengths, the closely related B. 

 nectabanus and B. cantori have obviously different pigmenta- 



