pjb05 wrote on Oct 23^rd, 2008 at 1:39pm:


"The longer they run" doesn't make them long enough that's why Walter comes through as illogical.

"He's a fisheries advocate." That is exactly what he appears to be.

"you may as well hang up your fishing rod"
Yes if commercial fishing continues in our river.

freediver wrote on Oct 23^rd, 2008 at 4:34pm:


Then demonstrate it. You haven't even come close to giving a plausible argument.

"The longer they run" doesn't make them long enough that's why Walter comes through as illogical.

So long running studies aren't long enough for you but short term cherry picked one are? 

"He's a fisheries advocate." That is exactly what he appears to be.

Angling is part of fisheries Tallowood. We are lucky we have someone of his credentials to go into bat for us. For a lot of popular species in Australia the rec take equals or exceeds the commercial take!

"you may as well hang up your fishing rod"
Yes if commercial fishing continues in our river.

I thought we were talking about the GBR? What river are you talking about? Do you just want no commercial fishing in your river and happy for it to happen in someone elses backyard?

Angling is part of fisheries Tallowood. We are lucky we have someone of his credentials to go into bat for us. For a lot of popular species in Australia the rec take equals or exceeds the commercial take!
Recreational fisherman have hips more restrictions then commercial.

But there are a lot more recs than commercial fishermen. Eg there are only 1200 commericial fishermen in NSW waters and over a million anglers.

So long running studies aren't long enough for you but short term cherry picked one are?  
Did Walter defined clearly what is "long enough"?

Well the one and a half to two years claimed isn't long enough. PS there are plenty of peer reviewed papers which claim you need at least a generation to pass before you can claim an effect from a marine reserve.

freediver wrote on Oct 23^rd, 2008 at 6:15pm:



Prof Ray Hilborn wrote one such paper. When I put up an article in which he refered to it you just said he didn't know what he was talking about. Refer also to the 'Burdens of Proof' paper.

freediver wrote on Oct 23^rd, 2008 at 6:33pm:


His language was very clear, so he 'must' be wrong then. Never mind he is a Professor in fisheries science and you have no qualifications in the field whatsoever (plus haven't even read his paper).

The Burdens of Proof paper also covers this issue:

(While such speculations are intuitive, they often appear in the literature as logically true assertions. However, these deceptively reasonable speculations are each dependent on underlying
assumptions about behaviour, ecology and the fishery. It is logically true that preventing fishing in particular areas will eliminate direct fishing mortality and stop the destruction of habitat caused
by contact fishing gears (Collie et al. 2000). However, it is imprudent to make untested assertions about the primary consequences of reserve protection on fish population dynamics, and then to
extrapolate those effects to fishery-level predictions. Typical predictions of fishery enhancement could be invalidated for a number of reasons, including displaced fishing effort around the reserve
boundary (Parrish 1999), recruitment limitation (Doherty & Fowler 1994), self-recruitment rather than larval export (Leis 2002), irreversible changes in species assemblages, and any number of
unknown causes due to the underlying complexity of the ecosystem. Without empirical substantiation, predictions of fishery enhancement are deductions based on circumstantial evidence and ancillary information. Furthermore, even if model assumptions are logically correct, it is not sufficient to test only for the existence of reserve effects. Of real relevance is the magnitude of an effect and the certainty (or lack thereof ) that surrounds estimates of it.

Detection of recovery of fish density in marine reserves often suffers from lack of rigour in the design of field surveys (Hurlbert 1984; Stewart-Oaten et al. 1986; Underwood 1990, 1993). As Underwood (1990) pointed out, studies lacking replication cannot be logically interpreted.

In the marine reserve context there are many reasons why researchers might have limits on their sampling designs. However, a critical evaluation of the experimental designs employed by many
published studies brought to light the following problems with replication and lack of control sites:

(1) insufficient sample replication (for example only one site sampled inside and outside a reserve, or no control sites sampled at all);
(2) spatial confounding (for example all control sites located only at one end of the reserve, so that comparisons are confounded by unknown location effects);
(3) lack of temporal replication (most studies consist of surveys done at only one time);
(4) lack of replication at the reserve level limiting the generality of results (although in many cases this reflects the number of reserves available); and
(5) non-random placement of reserves, i.e. often reserves are sited to include ‘special’ or unique features, which causes difficulties in selecting valid control sites (this is obviously no fault of
the researchers).

Not at all.