Meeting Abstract
Little is known about the reproductive biology of oarfish (Regalecus russelii). In the last three years, as many oarfish have been discovered on southern California beaches; two females (Oct. 2013: 4.4m TL, June 2015: 4.3m TL) and one male (Aug. 2015: 4.3m TL, 82.4kg body weight). The ovaries from the June 2015 fish weighed 10.99kg and were 2.14m in length. The ovaries were bifurcated at the anterior-most end, attached by a thick connective tissue 111.0cm from the anterior end, and completely fused 161.0cm from the anterior end. Gonadal fragments from the oarfish were fixed, histologically processed and embedded in paraffin wax. Histological tissue sections from the Oct. 2013 female contained 52.5% primary, 44.9% secondary, and 2.6% tertiary ovarian follicles. Tissue sections from the June 2015 female contained 33.5% primary, 62.3% secondary, and 4.2% tertiary ovarian follicles. No mature or ovulated oocytes were present in ovarian tissue from either female. The compositional differences in ovarian follicles may indicate that the Oct. 2013 oarfish may have previously spawned, whereas the June 2015 oarfish had ovarian follicles that were progressively developing. The testes from the Aug. 2015 fish weighed 40g. The left testis was 64.7cm in length and the right testis was 55.9cm. The testes were attached by connective tissue but not fused. Histological examination indicated that the male may have recently spawned; no spermatozoa were present within the testes and only a few spermatids were visible. The testes were primarily populated with primary spermatocytes. The incredible size disparity between the gonads of similarly sized fish is very interesting. The gross morphological and histological descriptions of these three oarfish may significantly contribute to our understanding of the reproductive biology of oarfish.
