19 



Abstract — Annual potential fecun- 

 dity, batch fecundity, and oocyte 

 atresia were estimated for Atka 

 mackerel iPleurogrammus monopte- 

 rygius^ collected in Alaskan waters 

 during 1993-94. Atka mackerel were 

 assumed to be determinate spawners 

 on the basis of decreasing fecundity 

 after batch spawning events. Histo- 

 logical examination of the ovaries 

 indicated that oocytes in the vitel- 

 logenic stage and higher had been 

 spawned in the current spawning 

 season. For an average female of 40 

 cm, potential annual fecundity was 

 estimated to be 41,994 eggs, aver- 

 age batch size (i.e., batch fecundityl 

 was estimated to be 6689 eggs, and 

 there were 6.13 batches per spawn- 

 ing season. Atresia was estimated by 

 examining postspawning specimens 

 and was found to be substantial. The 

 average amount of atresia for a 40- 

 cm fish was estimated to be 11,329 

 eggs, resulting in an estimated real- 

 ized fecundity of only 30,664 eggs and 

 4.64 batches of eggs per spawning 

 season. 



Annual fecundity, batch fecundity, 

 and oocyte atresia of Atka mackerel 

 iPieurogrammus monopterygius) 

 in Alaskan waters 



Susanne F. McDermott (contact author)^ 

 Katherine P. Maslenikov^ 

 Donald R. Gunderson^ 



Email address for S F. McDermott: Susanne. McDermott@noaa gov 



' National Marine Fisheries Service 

 Alaska Fisheries Science Center 

 7600 Sand Point Way NE 

 Seattle, Washington 98115 



^ University of Washington 

 School of Aquatic and Fisheries Sciences 

 Box 355020 

 Seattle, Washington 98195 



Manuscript submitted 22 April 2004 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 15 March 2006 by the Scientific Editor. 



Fish. Bull. 105:19-29 (2007). 



The reproductive biology of Atka mack- 

 erel (Pleurogrammus monopterygius) 

 is characterized by batch spawning by 

 females and nest-guarding by males. 

 This member of the greenling family 

 (Hexagrammidae) is distributed in 

 Russian and Alaskan waters where it 

 is usually found in dense aggregations 

 and associated with areas of fast cur- 

 rents, such as the passes between the 

 Aleutian Islands (Lowe et al., 2002). 

 Peak spawning occurs from July 

 through October in Alaskan waters 

 (McDermott and Lowe, 1997) and from 

 June through September off Kam- 

 chatka (Zolotov, 1993). Batches of adhe- 

 sive eggs are spawned in rock crevices 

 and are guarded by males until they 

 hatch (Gorbunova, 1962; Zolotov, 1993). 

 Studies with archival tags have indi- 

 cated that males guard nests for 3-4 

 months (Nichol and Somerton, 2002). 

 Batches of eggs in different phases of 

 development were found within one 

 nest, indicating a promiscuous mating 

 system (Zolotov and Tokranov, 1989; 

 Zolotov, 1993; Lowe et al., 2003). 

 Atka mackerel females spawn their 

 annual complement of eggs in several 

 batches over the course of the spawn- 

 ing season. Zolotov (1993) reported 

 that females spawn an average of 

 three batches of eggs per season and 

 that there is at least a two-week hia- 

 tus between spawnings in Kamchat- 



kan waters. To estimate the number 

 of batches spawned by a female, it is 

 necessary to estimate annual fecundi- 

 ty and batch fecundity. Annual fecun- 

 dity is defined as the total number of 

 eggs spawned by a female in a single 

 year and batch fecundity is defined 

 as the numbers of eggs released at 

 one time (Nichol and Acuna, 2001). 

 Direct estimation of annual fecun- 

 dity is possible if the number of eggs 

 to be spawned that season is fixed 

 or determinate (Hunter et al., 1985). 

 Fish with determinate fecundity are 

 described as showing a well-defined 

 hiatus (or gap) in oocyte-size distri- 

 bution between the advanced oocytes 

 that will be spawned that year and 

 the immature oocytes that will not 

 develop until the following spawn- 

 ing seasons (Hunter et al., 1985). 

 Species that are characterized by 

 continuous oocyte development and 

 oocyte-size distributions have often 

 been described as indeterminate 

 spawners (Hunter et al., 1985) that 

 have the ability to develop unyolked 

 oocytes continually and add them to 

 the standing stock of advanced-yolked 

 oocytes even after spawning begins. 

 Hunter and Macewicz (2001) stated 

 that potential fecundity can be es- 

 timated if three key requirements 

 are met: 1) one can identify a cer- 

 tain standing stock or size range of 



