Alternative reproductive tactics and growth of male cunners, Tautogolabrus adspersus (Walbaum), in Newfoundland

• Main Author: Gravel, Carolyn Mary.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1987
• Subjects: Norris Point; Newfoundland
• Online Access: https://research.library.mun.ca/7950/; https://research.library.mun.ca/7950/1/Gravel_CarolynMary.pdf; https://research.library.mun.ca/7950/3/Gravel_CarolynMary.pdf

Alternative reproductive tactics utilized in two separate populations of the Newfoundland male cunner, Tautogolabrus adspersus, were investigated for tradeoffs between sperm production and somatic growth. One population in Broad Cove, Conception Bay, consisted of pair spawning territorial males and nonspawning preterritorial males. A second population at Norris Point, Bonne Bay, contained group spawning nonterritorial males. The parameters measured from prespawning and postspawning samples of both populations were total length, eviscerated body weight, gonad weight, and age. These variables and a gonadosomatic index were tested for differences between the three reproductive types of males mentioned above. Results indicated that gonad weights and gonadosomatic indices per age class were significantly greater in group spawning males than in preterritorial males younger than 15 years. The same was found for gonad weight per unit body weight at age, thereby supporting the prediction that group spawners invest heavily in sex products early in life. Group spawning provides an opportunity for a female's eggs to be externally fertilized by many males, and large gonadal investments in group spawning males are probably a result of sperm competition. -- Length and body weight at age of the male group spawning population at Norris Point were significantly less than those of the preterritorial male population at Broad Cove. Body size differences were slight, however, suggesting no significant tradeoff between high sperm production and decreased somatic growth rate. A tradeoff between high sperm production and reduced longevity of group spawning males was suggested by the absence of older (> 9 years) males at the group spawning site (Norris Point) as compared to high frequencies of similar aged males at the pair spawning site (Broad Cove). Age frequencies of females were the same between both populations. -- Within the Broad Cove population, territorial males invested more energy in gonads than preterritorial males. ...