458 



Fishery Bulletin 9 1(3), 1993 



sp., an unidentified caligoid copepod, and juveniles of 

 an unidentified gnathiid isopod) found in the epipe- 

 lagic and seamount armorhead collected in June 1985 

 and August 1986. Subsequent examinations of 

 armorhead were restricted to the gills where M. 

 macropharynx were exclusively found. Specimens of 

 M. macropharynx were readily distinguished from 

 Trochopus sp. by the disk-shaped opisthaptor of the 

 latter monogenean. All specimens of M. macropharynx 

 were initially identified as that of M. sebastis though 

 the pharynx of these specimens appeared to be unusu- 

 ally large 1 . During the review process, a new species 

 description (Mamaev, 1989) of the monogenean M. 

 macropharynx collected in 1969-70 from P. richardsoni 

 (=P. wheeleri) in the Hawaiian Islands region was 

 brought to the attention of the senior author. Subse- 

 quently specimens initially identified as M. sebastis 

 were re-examined and all found to be M. macro- 

 pharynx 2 . The large pharynx (in relation to the 

 anterior suckers) of M. macropharynx distinguishes 

 this species from all other species of Micocotyle 

 (Mamaev, 1989). Each M. macropharynx was staged 

 as either immature or potentially mature, based on 

 absence or development of the paired yolk ducts, re- 

 spectively. These organs are the last to develop before 

 egg development in the related species M. sebastis 

 (Thoney, 1986). All parasite taxa were saved and stored 

 in 70% ethyl alcohol. Prevalence and mean intensity 

 of M. macropharynx in seamount armorhead were com- 

 puted for each sampling period. Following the termi- 

 nology defined in Margolis et al. (1982), prevalence 

 (expressed as a percentage) refers to the number of 

 host species infected with a particular parasite spe- 

 cies, divided by the number of hosts examined; and 

 mean intensity is derived by dividing the total number 

 of a particular parasite species by the number of indi- 

 vidual hosts infected by that parasite. Prevalence and 

 mean intensity data from seamount armorhead were 

 partitioned into two FI groups of <0.26 and >0.26. This 

 grouping is based on the observation that 0.26 was the 

 lowest FI found for epipelagic armorhead in this study 

 and thus a possible minimum FI for newly arrived 

 seamount recruits. 



Liver and visceral fat weights were also determined 

 for the 27 epipelagic armorhead >27.5cm FL (of com- 

 parable length to seamount individuals) and 410 sea- 

 mount armorhead collected during October 1986 (n = 

 115) and January (n = 195), July (n = 18), and Novem- 

 ber 1988 (n = 82). Liver and visceral fat deposits were 



R. R- Payne, Department of Biological Sciences, Biola Univ., La 

 Mirada, CA, personal commun. 1988. 



-R. R. Payne, Department of Biological Sciences, Biola University, 

 La Mirada. CA, pers. commun. 1992. 



removed from the body cavity, blotted dry, and weighed 

 to the nearest 0.1 g. Liver and visceral fat weights are 

 expressed in relation to total body weight and referred 

 to as the hepatosomatic index (HSI) and visceral fat- 

 somatic index (VFSI), respectively. Data was arcsine 

 transformed and tested for normality with the Lilliefor's 

 method of the Kolmogorov-Smirnov test (Wilkinson, 

 1990). Sample means were compared by either t-test, 

 or by Mann-Whitney test if samples remained non- 

 normal (Wilkinson, 1990). 



Estimates of the proportion of recruits-of-the-year 

 to the total SE Hancock armorhead population during 

 each sampling period were based on stock-assesssment- 

 derived FI distributions of the armorhead population. 

 That proportion of the FI distribution >0.26 were con- 

 sidered recruits-of-the-year. Data and procedures used 

 to calculate the population FI distribution are presented 

 in Somerton and Kikkawa (1992). The proportion of 

 recruit-of-the-year armorhead in each sampling period 

 un-infected by mature stages of M. macropharynx was 

 estimated from results of the prevalence data for those 

 armorhead (from samples examined for M. macro- 

 pharynx) with a FI >0.26. 



Results 



Microcotyle macropharynx were not present in any of 

 the 53 epipelagic armorhead examined but were present 

 in all 775 seamount armorhead with FI <0.26 and in 

 417 (93.7%) of 445 specimens with FI >0.26. Among 

 seamount armorhead with FI <0.26, both the combined 

 (irrespective of maturity stage) category and the im- 

 mature and mature stage of M. macropharynx were 

 highly prevalent (>75%) in all nine sample periods 

 surveyed (Table 1). A similar pattern of high M. 

 macropharynx prevalence was found among the sea- 

 mount armorhead with FI >0.26 although instances of 

 lower prevalence appear during the two earliest sample 

 periods (Table 1). Mean intensity of immature M. 

 macropharynx in both FI groups was considerably lower 

 in each sample period than the corresponding mean 

 intensities of the mature stage and combined category 

 (Table 2). Mean intensity of mature stage M. macro- 

 pharynx in each sample period and FI group was suffi- 

 ciently high to ensure easy detection in armorhead 

 infected with mature stage individuals of this monoge- 

 nean. A wide range in sizes of M. macropharynx, in- 

 cluding mature stages with eggs, was present among 

 the gills of armorhead, indicating that this parasite 

 has a monoxenous life cycle. 



Seamount armorhead without mature M. macro- 

 pharynx represented 5.2% (64) of the 1,220 fish exam- 

 ined. Among those seamount armorhead found un- 



