Armstrong et al . Age, growth, and reproduction of Lophius amencanus 



221 



for the two species; in fact, it would be expected that 

 the age- and length-at-maturity for L. piscatorius 

 would probably be greater, as suggested here. 



Data on gonad condition and the gonasomatic index 

 indicate that spawning takes place in May-June in the 

 area from Cape Hatteras to Southern New England. 

 Because samples were collected and pooled from 

 throughout this entire region, a seasonal progression 

 of spawning from south to north as suggested in the 

 literature cannot be demonstrated. Testes appear to 

 develop earlier and remain ripe longer than ovaries. 

 Fulton (1898) found the same to be true for L. pisca- 

 torius. This suggests that males may be multiple 

 spawners. Multiple spawning in males would increase 

 the chances of a ripe female encountering a ripe male, 

 and thereby spawning successfully. It also serves to 

 equalize the energetic investment of the sexes in 

 reproduction. It appears that the investment of females 

 is relatively high. The GSI was as high as 50%. Tsi- 

 menidis (1980) found values as high as 37% for the 

 Mediterranean goosefish L. budegassa. A large part of 

 the ovarian weight is composed of the mucogelatinous 

 material that forms the veil. The caloric value of this 

 material is unknown, but probably is rather low because 

 of its low density and apparently high water content. 

 However, the large amount of this material, combined 

 with the great number of eggs produced, represents 

 a sizeable energetic contribution by the female to 

 reproduction. 



Histological examination of the goosefish testes 

 showed that spermatogenesis and the internal struc- 

 ture are not remarkably different from other teleosts. 

 It also confirmed the validity of macroscopic staging 

 of testes in the field. Examination of ovaries showed 

 that oogenesis is similar to other teleosts but the struc- 

 ture of the ovary is somewhat different. The most 

 significant differences were the presence of stalk-like 

 lamellae containing the developing ova, and epithelium 

 lining the lumen which is responsible for secreting the 

 mucogelatinous matrix. Fulton (1898) was the first to 

 suggest this mechanism of veil formation in the 

 lophiids. His figures and descriptions of the histology 

 of the ovaries of L. piscatorius indicate they are iden- 

 tical to those from L. americanus seen here. Rasquin 

 (1958) provided detailed descriptions and photographs 

 of the ovaries of two species of antennariid anglers 

 (Antennariu^, Histrio) and one species of ogcocephalid 

 angler. These lophiiform species are known to produce 

 egg veils. Although they are all only a fraction of the 

 size of L. americanus and L. piscatorius, the histology 

 of their ovaries was virtually identical to their larger 

 relatives, including the presence of stalk-like ovigerous 

 lamellae and secretory epithelium. It is reasonable to 

 assume that all members of the order Lophiiformes 

 known to produce egg veils have similar ovaries. This 



character may be useful in verifying veil production in 

 some of the deepwater lophiiform families for which 

 veil production has been assumed but not verified. 



Pietsch and Grobecker (1980) suggest that the egg 

 veil is an excellent device for broadcasting a large 

 number of eggs over great geographical distances. In 

 addition, the buoyancy of the veil causes the eggs to 

 develop in relatively productive surface waters. 



There seem to be additional selective advantages to 

 the egg veil as well. It may function in facilitating fer- 

 tilization of the eggs. When a veil is first extruded from 

 the female, it absorbs a large quantity of water. As 

 water is absorbed, sperm may be drawn into the egg 

 chambers through the small circulation pores in the 

 veil, thereby insuring fertilization. The veil likely func- 

 tions by several methods in the protection of the eggs 

 and embryos, since the embryos remain in the egg 

 chamber for 2-3 days after hatching (Dahlgren 1928). 

 Predators such as zooplankton are physically excluded 

 from the egg chambers by the small size of the circula- 

 tion pore. The veil may reduce or eliminate olfactory 

 cues, thereby eliminating predators locating food items 

 by this method. Wells (1977) suggests that the jelly coat 

 of yellow perch Perca flavescens spawn may act in a 

 similar manner. Finally, the mucogelatinous material 

 of goosefish egg veils may be toxic or repugnant to 

 potential predators. Newsome and Tompkins (1985) 

 found that the egg mass of yellow perch contain some 

 compound(s) that are not toxic but seem to deter pred- 

 ators. While such a protective device is rare among 

 teleosts (Fuhrman et al. 1969, Orians and Janzen 1974), 

 the presence of toxic or unpalatable compounds within 

 the jelly coat of amphibian egg masses is well known 

 (Licht 1969, Ward and Sexton 1981). 



Age and growth 



Females and males have about the same weight-at- 

 length before maturity. After maturity the females are 

 slightly heavier than males because of their large 

 ovaries. As the ovaries ripen, weight differences be- 

 tween males and females become greater. The regres- 

 sion slopes for males and females approximate 3, imply- 

 ing isometric growth in the length-weight relationship. 

 Tsimenidis and Ondrias (1980) calculated very similar 

 length-weight regressions for L. piscatorius in the 

 Mediterranean Sea. 



Vertebrae appear to be valid aging tools for L. ameri- 

 canus. They satisfy all of Van Oosten's (1929) criteria. 

 Vertebrae can readily be located and removed from 

 goosefish and are relatively easy to prepare and read. 

 The annuli are readily discernible since only 3% of the 

 vertebrae were considered unreliable, and an inex- 

 perienced, independent reader agreed with the counts 

 in 80% of the readings he performed. 



