Hi all, as many of you regular readers to this site will now there is often a topic of conversation concerning the Dusky Flathead and the 70cm no take limit. There seems to be many a theory/oldwivestale/misinformation/opinion(call it what you want) about the topic. I was one of those with the wrong idea. Below is close carbon copy of a letter to the editor of a Marine Biology PHD student on the matter. While the outcome is still the same as most of what we thought, I think this is some very interesting reading and mostly likely the right information.
Happy reading..... Oh the letter was published in November 2007, Modern Fishing Magazine. A bit long but a good read just the same.
Cheers Chris
" I was reading the July 2007 issue of Modern Fishing and came across the letter 'Lizard Lore', from a fellow reader (Anthony Willebrands-DL) and thought I may be able to provide a few answers in regards to the Flathead biology. I'm currently finishing my PHD through the centre for Fish and Fisheries Research at Murdoch University in Western Australia, in which I am investigating the biology of the Yellowtail Flathead and the Western Blue Groper and Blue Morwong.
During this study of the Yellowtail Flathead, (Platycephalus endrachtensis), in the Swan river estuary in Perth, we found several characteristics that Anthony Willebrands and other fellow Flathead lovers may like to know. Even though the Yellowtail Flathead can not reach the extraordinary lengths and weights to that of the Dusky Flathead, it does share the same characteristics of females and males having markedly different growth rates. The females and males of the Yellowtail Flathead attain a maximum length of 615mm and 374mm respectively. If you were only to see this result , you could be forgiven for assuming that this species is a protandrous hermaphrodite( male and female sex change). However, we also found that both sexes are present at all age classes from a age of one year old to the maximum of 9 years, recorded for both sexes.
Further investigation of the reproductive organs, overies and testes of Yellowtail flathead found no evidence of male and female reproductive tissue occurig together-a key indication of possible sex change. Our conclusion was that Yellowtail Flathead were dioecious ( Speparate sexes), with females and males possessing markedly different growth rates.
In other studies of Flatheads in the genus Platycephalis, including the Dusky (P.fuscus), Southern blue-spotted Flathead(P.speculator), Sand Flathead (P.Bassensis), Tiger Flathead(P.richardsoni) and the bar tailed flathead(P.indicus), similar results of femailes attaining a larger size have been found. Furthermore, none of these scientific studies found any evidence of sex change in these species.
The thought that Dusky Flathead may change sex may could have come about from literature describing the biology of other members of the Platcephalid family, including several species found in Japanese waters, such as the Lizard Flathead(Inegocia japonica). They do change sex from male to female. In species where the large fish are females not just in Flathead, it is imperative that we try to protect these large fish because it is these individuals that have the greatest reproductive output; they are able to produce hundreds of thousands or even millions of eggs.
To think that these large Dusky Flatheads are barren is not correct. Kind Regards Pete C.
Peter Coulson, Centre for Fish and Fisheries Research , South St. Murdoch, WA 6150.
There it is boys and girls a real scientific reason behind fish conservation. Maybe someone at the EPA could adopt the same. I doubt it.
Cheers Chris
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Originally Posted by DICER
It's just that those big ones you were throwing back were always female an didnt have a sex change so to speak. They are the most productive fish and still need to be returned.
