Age and growth of two endemic flatfish (Colistium guntheri and C. nudipinnis) in central New Zealand waters

Abstract

Brill (Colistium guntheri) and turbot (C. nudipinnis) were aged by counting opaque growth zones in whole and sectioned otoliths. Zones counts from whole otoliths under-estimated age compared with counts from thin otolith sections. Other species of flatfish that have previously been aged from whole otoliths should be re-examined for evidence of age under-estimation, which may be common in species with thick otoliths. Marginal analysis of thin sections supported the hypothesis that one translucent and one opaque zone are formed each year in brill aged 5–10-years old. Marginal analyses for brill greater than 10 years of age, and for turbot, were inconclusive. However, 2+ and 3+ captive-reared turbot deposited the expected number of opaque zones from hatching. Both species grow rapidly for the first three years of life before growth slows appreciably. Turbot grow faster and larger than brill, and females grow faster and larger than males in both species. Growth is minimal in fish older than five years. Maximum observed ages were 21 years for brill and 16 years for turbot.

An assessment of otoliths, dorsal spines and scales to age the long-finned gurnard, Lepidotrigla argus , Ogilby, 1910 (Family: Triglidae)

“…This result does not conclude that both structures are suitable for age estimation, as repeatable non-bias age readings can still be inaccurate (Campana, 2001). Sectioned otoliths were found, however, to have much clearer growth increments and were easier to interpret than whole otoliths, which is consistent with previous studies (Ferreira and Russ, 1994;Stevens et al, 2005). Comparison of final ages for sectioned and whole otoliths revealed that an ageing bias was evident between the two methods.…”

“…However, caution must be exercised when using whole otoliths to determine the age of fish. Firstly, the resolution of growth increments in thick otoliths can often be poor (Stevens et al, 2005); secondly, it is suggested that areas of pigment can be visible in whole otoliths which are not visible in sectioned otoliths (Fowler and Short, 1998); and thirdly, reflected light used to examine whole otoliths can cause a halo effect around the edge of the otolith which can make edge determination difficult. Thus, sectioned otoliths are more often used to estimate age than whole otoliths.…”

Biological characteristics of the primitive flatfish Indian halibut (Psettodes erumei) from the tropical northeastern Indian Ocean, including implications of the use of incorrect aging methods on mortality estimates

“…Mean monthly sea-surface temperatures in waters off the Pilbara coast, for the 1° grid block of 19-20°S, 117-118°E, were calculated from monthly values in 2010-2015 obtained from the Koninklijk Nederlands Meteorologisch Instituut Climate Explorer (available from website), which employs data from Reynolds optimum interpolation analysis of sea-surface temperatures (Reynolds et al, 2007). Daily lengths of days for the town of Karratha (~22°S, 117°E), on the Pilbara coast, obtained from timeanddate.com (day length data available from website), were employed to generate mean monthly day lengths for 2014 and 2015.…”

“…The importance of choosing the appropriate aging structure and then validating the periodicity of growth increments has been made clear (Beamish and McFarlane, 1983;Campana, 2001), as have the implications of not doing so (c.f. Mace et al, 1990;Smith et al, 1995). Previous age estimates for Indian halibut have been derived from counting growth rings in vertebrae (Edwards and Shaher, 1991), scales (Druzhinin and Petrova, 1980), and whole otoliths (Das and Mishra, 1990), and none of those methods were validated; ages also have been estimated by examining trends displayed by monthly length frequencies (Silvestre and Garces, 2004;Gilanshahi et al, 2012).…”

“…The use of vertebrae to age fish has been associated with large discrepancies in age estimates between readers (e.g., Esteves et al, 1995;Filmalter et al, 2009) and interpretation difficulties (e.g., Baker and Timmons, 1991;Marriott and Cappo, 2000;Khemiri et al, 2005). Although scales have been shown to be a useful aging structure for which removal is not lethal (e.g., Robillard and Marsden, 1996;Khan and Khan, 2009), the accuracy of ages derived from counts of growth zones on scales is questionable (Beamish and McFarlane, 1983). Even though whole otoliths are suitable to age short-lived species (e.g., Fairclough et al, 2000;Kornis et al, 2017), for many fishes, including a number of flatfishes, it has been acknowledged that ages based on whole otoliths are often underestimated (e.g., Campana, 1984;Forsberg 2 ;Stevens et al, 2005;Albert et al, 2009).…”