Biology of the Foxfish Bodianus frenchii, an exceptionally long-lived, monandric protogynous labrid, including regional comparisons
Travers, M.J., Potter, I.C., Clarke, K.R., Newman, S.J. and Hutchins, J.B. (2009) Latitudinal and bioregional patterns of fish assemblages in north-western Australia. In: 8th Indo Pacific Fish Conference and 2009 ASFB Workshop and Conference, 31 May - 5 June 2009, Fremantle, Western Australia.
Steve Cossington, Alex Hesp & Ian Potter
Photo : Barry Hutchins Bodianus frenchii
• Medium-sized (480mm TL) temperate labrid
• In sub-genus Verreo, which contains 7 temperate Bodianus species • Excellent eating and thus targeted by recreational fishers
• Unusual disjunct distribution in southern half of Australia
• Environment of lower west and south coasts of WA differ
Photo : Barry Hutchins Some characteristics of labrids
• Very speciose family
• Found in both temperate and tropical waters and often over reefs
• Species mainly short lived
• Maximum age is 70 years for the temperate Achoerodus gouldii
• Many species are protogynous hermaphrodites, i.e. change sex from female to male
• Carnivorous Ageing of Bodianus frenchii
• Number of opaque zones in sectioned otoliths
• Marginal increment analysis validated that a single opaque zone is formed annually in otoliths
• Schnute growth curves fitted to lengths at age
Whole otolith Sectioned otolith Periphery of otolith Age and Growth
500 South coast Maximum age is 78 years! 400 Several fish > 50 years old 300 Rapid initial growth on both coasts West coast 200 Lengths at age typically 100 greater on the south than Total length (mm) west coast 0 0 10 20 30 40 50 60 70 80 Age (years) the south coast both coasts years,100%mature in fish > 237mm years,100%mature in fish 279> mm Reflects faster growth on south coast Maturityattained atayounger ageon Maturityattained at similar lengths on L South coast L Lower coast west 50 50 = 236mm = 50% mature, by4 = 245mm, 50%mature by 8 Lengths Lengths and ages at maturity - 9 - 5
Percentage frequency Percentage frequency 100 100 20 40 60 80 20 40 60 80 0 0 West coastWest 0-1 4 0 0 coastWest 13 0 40 0 10 Totallength (mm) 3 80 2
Age (years) 3 5 3 10-11 2 120 2 4 4 2 160 5 9 8 12 200 3 3 20-21 8 240 4 7 16 5 280 17 7 20 8 320 14 9 13 >30 > 360 South coast 1 0 0 South coast 0-1 10 0 7 40 0 1 7 Totallength (mm) 80
Age (years) 0 3 0 10-11 3 120 3 8 2 2 160 2 9 1 10 200 1 3 5 20-21 240 9 1 10 3 280 9 6 5 6 320 17 11 33 >30 > 360 L smallest = male 245mm, South coast L smallest = male mm, 291 Lower west coast length and age prevalence with of males both in Strong trend increasing than length Sex change related age more to 0.001) length on south the coast ( Sex change attained greaterata on both coasts( Sex change agesattained similar at 50 50 = 365mm 365mm = , = 327mm, 327mm, = Lengths and ages at sex change A A 50 50 p = 28.7 28.7 = years, > 0.05) > = 29.2 29.2 = years p <
Percentage frequency Percentage frequency 100 100 20 40 60 80 20 40 60 80 0 0 West coast West 0 0 coast West 0-5 26 0 10 40 0
Total length (mm) 2 10-14 8 80 3 44 120 3
Age (years) 2 43 4 20-24 160 5 56 8 200 3 30-34 51 3 16 240 5 26 40-44 20 280 34 54 8 320 73 11 45 50-54 360 24 5 400 12 3 5 >60 440 4
South coast 0 0 South coast 0-4 28 0 33 40 0 1 23 80 10-14 Total length (mm) 1 2 43 120 3 Age (years) 22 2 20-24 160 3 28 2 200 3 30-34 26 11 16 240 15 21 40-44 12 280 18 20 13 320 30 8 37 50-54 360 44 8 400 41 5 31 >60 440 9 Protogyny
• Length by which all females are mature is less than the length of the smallest male
• This provides strong evidence that Bodianus frenchii is a monandric protogynous hermaphrodite
Bisexual gonad Testis Spawning season and reproductive investment
• Spawning season on both coasts is from October to February
• Gonad weights during spawning season far greater on south than west coast
• Reflected in far greater batch and potential annual fecundities
Females - West coast Females - South coast 7 9 8 15 22 16 20 9 6 1712 5 18 1813 1914 28 9 13 11 9 7 25 100 25 100
Legend: ovarian stages 20 80 20 80
Developing/Maturing 15 60 15 60
Mature/Spawning 10 40 10 40
Percent
Percent
Spent/Recovering 5 20 5 20
0 0 0 0
Standardised gonad weight (g) weight gonad Standardised J A S O N D J F M A M J (g) weight gonad Standardised J A S O N D J F M A M J Month Month Main findings for Bodianus frenchii
• Exceptional longevity. Max. age = 78 years
• Maturity is related more to length than age
• Sex change is related more to age than length
• Monandric protandrous hermaphrodite
• Regional differences in • Growth • Length and age at maturity and sex change • Fecundity
• South coast may provide better environment for growth and reproduction Acknowledgments
• Peter Coulson for help with collection of fish
• John Stuart for collection tips and local knowledge around Esperance
• Gordon Thompson for the preparation of all histological slides