Secondary sexual characteristics in codfishes (Gadidae) in relation to sound production, habitat use and social behaviour

Figures & data

Table I. Summary table of information on adult habitat, social behaviour and sexual dimorphism in codfishes (Gadidae); maximum size (total length, cm); reproductive behaviour (RB); presence of, and sexual dimorphism in drumming muscles (D, drumming muscle present, SD, sexually dimorphic drumming muscle), and the presence of sexual pelvic-fin length dimorphism (PFD) sorted according to habitat. Under ‘Habitat’, D denotes demersal, P denotes pelagic, and BeP denotes bentho-pelagic. Under ‘RB’, A denotes the presence of aggressive behaviour and C courtship behaviour during reproduction. Under D/SD the first Y denotes the presence of drumming muscles and * indicates that actual sound production of the species has been recorded. The second Y indicates that the drumming muscle have been shown to be sexually dimorphic. ** Juvenile but not adult saithe possess a drumming muscle. N denotes the absence of a drumming muscle/pelvic-fin dimorphism. ‘–’ Indicates that the species in question has not been examined for this particular trait. Data on habitat and maximum size (cm) were obtained from the FAO species catalogue (Cohen et al. 1990).

Species	Habitat	Size	RB	D/SD	PFD	References
Melanogrammus aeglefinus (Linnaeus, 1758)	D	100	AC	Y*/Y	N	Hawkins & Rasmussen 1978; Hawkins & Amorim 2000; this study
Raniceps raninus (Linnaeus, 1758)	D	30	–	Y*/–	–	Hawkins & Rasmussen 1978
Gadus ogac Richardson, 1836	D	70	–	Y/–	–	Hawkins & Rasmussen 1978
Boreogadus saida (Lepechin, 1774)	D	40	–	Y/–	–	Hawkins & Rasmussen 1978
Molva molva (Linnaeus, 1758)	D	200	–	Y/–	–	Hawkins & Rasmussen 1978
Molva dypterygia (Pennant, 1784)	D	155	–	Y*/–	–	Hawkins & Rasmussen 1978 – only examined in males
Brosme brosme (Ascanius, 1772)	D	110	–	Y/–	–	Hawkins & Rasmussen 1978
Gaidropsarus mediterraneus (Linnaeus, 1758)	D	50	–	Y*/–	–	Almada et al. 1996
Gaidropsarus vulgaris (Cloquet, 1824)	D	60	–	N	–	Hawkins & Rasmussen 1978
Ciliata mustela (Linnaeus, 1758)	D	25	–	N	–	Hawkins & Rasmussen 1978
Enchelyopus cimbrius (Linnaeus, 1776)	D	41	–	N	–	Hawkins & Rasmussen 1978
Microgadus proximus (Girard, 1854)	D	30	–	N	–	Hawkins & Rasmussen 1978
Eleginus navaga (Walbaum, 1792)	D	42	–	N	–	Hawkins & Rasmussen 1978
Eleginus gracilis (Tilesius, 1810)	D	55	–	N	–	Hawkins & Rasmussen 1978
Pollachius virens (Linnaeus, 1758)	P	130	–	N**	Y	Hawkins & Rasmussen 1978, this study
Gadiculus argenteus Guichenot, 1850	P	15	–	N	–	Hawkins & Rasmussen 1978
Micromesistius poutassou (Risso, 1827)	P/BeP	50	–	N	Y	Andersen & Jákupsstova 1978; Hawkins & Rasmussen 1978; this study
Pollachius pollachius (Linnaeus, 1758)	P/BeP	75	–	Y*/–	–	Jonatan Nilsson, Institute of Marine Research, Bergen, Norway, pers., comm
Trisopterus esmarkii (Nilsson, 1855)	P/BeP	20	–	N	–	Hawkins & Rasmussen 1978
Trisopterus minutus (Linnaeus, 1758)	BeP	40	–	N	–	Hawkins & Rasmussen 1978
Trisopterus luscus (Linnaeus, 1758)	BeP	45	–	N	–	Hawkins & Rasmussen 1978
Gadus morhua Linnaeus, 1758	BeP	200	AC	Y*/Y	Y	Brawn 1961a,b; Morgan & Trippel 1996; Engen & Folstad 1999; Skjæraasen et al. 2006
Merlangius merlangus (Linnaeus, 1758)	BeP	70	AC	N	Y	Hawkins & Rasmussen 1978; Milic & Kraljevic 2011
Theragra chalcogramma (Pallas, 1811)	BeP	80	C	Y/–	–	Hawkins & Rasmussen 1978; Baird & Olla 1991; Onuki & Somiya 2006
Gadus macrocephalus Tilesius, 1810	BeP	100	N	N	–	Sakuri & Hattori 1996

Table II. Summary of morphological measurements. Mean (M) and coefficient of variation (CV) of total length (TL, cm), total weight (TW, g), drumming-muscle dry weight (DR, g) and lengths (cm) of the first (D1), second (D2), and third dorsal (D3) fin, pectoral (PF), pelvic (PL), pectoral (PF), and first (A1) and second (A2) anal fin (all lengths are given in cm). Numbers in parentheses indicate sample size. Not all fin measurements were conducted on each sample.

	Blue whiting				Haddock				Saithe				Cod
	♂ (10)		♀ (25)		♂ (50)		♀ (27)		♂ (56)		♀ (57)		♂ (48)		♀ (2)
	M	CV	M	CV	M	CV	M	CV	M	CV	M	CV	M	CV	M	CV
TL	24.9	0.06	25.8	0.05	49.8	0.16	53.1	0.13	65.0	0.21	60.6	0.21	70.9	0.09	68	–
TW	99	0.27	103	0.17	1450	0.48	2010	0.36	2806	0.67	2393	0.68	3570	0.23	3613	–
DR	–	–	–	–	2.2	0.57	0.37	0.55	–	–	–	–	0.50	0.68	0.16	–
D1	2.4	0.09	2.4	0.17	6.3	0.17	6.7	0.18	4.0	0.27	3.7	0.28	5.5	0.17	5.8	–
D2	2.1	0.14	2.4	0.14	3.4	0.35	3.5	0.16	3.2	0.29	2.9	0.29	4.4	0.22	4.6	–
D3	1.6	0.10	1.5	0.22	2.5	0.31	2.6	0.20	2.0	0.48	1.6	0.42	4.6	0.16	4.6	–
PF	3.0	0.14	3.1	0.10	5.2	0.26	5.7	0.16	5.3	0.22	4.9	0.25	6.6	0.11	6.5	–
PL	1.8	0.19	1.1	0.39	3.4	0.20	3.5	0.14	3.1	0.41	2.4	0.41	5.6	0.10	5.1	–
A1	1.8	0.15	1.9	0.14	3.7	0.22	4.1	0.18	3.8	0.27	3.5	0.30	4.9	0.25	4.9	–
A2	1.6	0.06	1.5	0.15	2.6	0.30	2.83	0.20	2.1	0.51	1.6	0.45	4.8	0.12	4.8	–

Figure 1.  Drumming muscle mass of male (grey) and female (black) (A) haddock (Melanogrammus aeglefinus) and (B) cod (Gadus morhua). The white point (A) indicates the ‘outlier’ male mentioned in the results. Note the different scales on the y-axes of both graphs.

Figure 2.  Pelvic-fin versus total length of male (grey circles) and female (black circles) (A) saithe (Pollachius virens) and (B) blue whiting (Micromesistius poutassou).

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