Editing Murray cod (section)

====Overfishing====
While extremely severe commercial and recreational overfishing in the 1800s and the early 1900s caused the first strong declines of Murray cod, [[overfishing]] by recreational fishermen, aided by inadequate fishing regulations, continues today and remains an extremely serious threat to Murray cod. The current size limit of 60&nbsp;centimetres in most states is inadequate now that scientific studies have documented average size at sexual maturity in Murray cod.<ref name=Nicol-et-al2005/> This and catch data and computer modelling exercises<ref name=Nicol-et-al2005/> on wild Murray cod stocks indicate measures such as raising the size limit to 70&nbsp;centimetres and reducing the bag and possession limits from 2 and 4 fish respectively to 1 fish are urgently needed to maintain the long-term viability of wild Murray cod populations. As of November 2014, the NSW Department of Fisheries has introduced a maximum size limit of 75&nbsp;cm for Murray Cod to provide protection for large breeding fish, as well as a new minimum size limit of 55&nbsp;cm.

Although angler effects are sometimes disregarded in the overall picture today, recent population studies have shown that while all year classes are well represented up to the minimum legal angling size (now 60&nbsp;centimetres in most states), above that size, numbers of fish are dramatically reduced almost to the point of non-existence in many waters.<ref name=Nicol-et-al2005/><ref name=Koehn2004/> Some emphasis has been made of the results of two small surveys which suggested a majority of Murray cod are released by anglers. However, there are valid questions as to the representativeness of these surveys: these surveys do not explain the dramatic disappearance of large numbers of young Murray cod at exactly the minimum size limit, and most importantly, any emphasis on these surveys miss the fundamental point — as a large, long-lived species with relatively low fecundity and delayed sexual maturity wild Murray cod populations are extremely vulnerable to overfishing, even with only modest angler-kill.<ref name=Nicol-et-al2005/><ref name=Koehn2004/> A tightening of fishing regulations for wild Murray cod, as referred to above, and a switch by fishermen to a largely [[catch and release]] approach for wild Murray cod would alleviate this problem.<ref name=Nicol-et-al2005/> Recognising these issues, in late 2014 the New South Wales and Victorian fishery departments amended their regulations so that a slot limit of 55 to 75&nbsp;cm now applies in these states. (i.e. only Murray cod between 55 and 75&nbsp;cm may be taken; those above and below this size range or "slot" must be released.) This measure should have positive effects for the Murray cod population by protecting and increasing the proportion of large breeding Murray cod.

Another issue is that Murray cod caught and released in winter, while developing their eggs, or in spring prior to spawning, resorb their eggs and do not spawn.<ref name=Rowland2005/><ref name=Lake1967/><ref name=Rowland1988>{{cite journal  | last = Rowland  | first = S. J.  | title = Hormone-induced spawning of the Australian freshwater fish Murray cod, ''Maccullochella peeli'' (Mitchell) (Percichthyidae)  | journal = Aquaculture  | volume = 70  | pages = 371–389  | year = 1988  | doi = 10.1016/0044-8486(88)90121-4  | issue = 4 | bibcode = 1988Aquac..70..371R }}</ref> This may be a minor issue compared to some of the other threats facing Murray cod, nevertheless, concerned fishermen try to avoid catching wild Murray cod at these times.<ref name=nfacod/> At this point in time a closed season is in place for the spring spawning period, during which anglers are not allowed to target Murray cod, even on a catch and release basis.