WA snapper and dhufish stock assessments: show us the data or stop calling it science

Let’s be clear from the outset. This is not research. This is not a competing stock assessment.

This is a plain-English examination of what the WA snapper and dhufish stock assessments leave out and why those omissions matter.

When regulators say two cornerstone demersal species are “in trouble”, that claim carries enormous consequences. Closures. Quota cuts. Access loss. Community impacts that last decades.

So the evidence trail matters.

Right now, what is being presented to the public looks less like science and more like guesswork. Or worse, selective disclosure.

What the WA snapper and dhufish stock assessments tell us, and what they don’t

Both the West Australian Snapper and West Australian Dhufish assessments rely heavily on one central claim:

Standardised commercial CPUE shows declining abundance.

That single sentence does an extraordinary amount of work.

Because the WA snapper and dhufish stock assessments do not show the data required to test whether that claim reflects fish biology or simply fewer people fishing.

What is missing and why it matters

Below is the data not published in either assessment summary. Not buried. Not redacted. Simply absent.

Each omission on its own is serious. Together, they undermine confidence in the conclusions reached by the WA snapper and dhufish stock assessments.

Effort and participation data

The most basic question in fisheries science is this:

Did catches fall because there are fewer fish, or because fewer people are fishing?

Yet the WA snapper and dhufish stock assessments do not publish:

• the number of active vessels per year

• the number of active licences per year

• days fished, trips, hours, hooks or shots

• changes in targeting behaviour

• effort displacement caused by closures

If participation collapses, landings fall even if biomass does not.

Without effort data, catch trends are meaningless.

The actual CPUE series

Both assessments state that CPUE was “standardised” and used as an index of abundance.

But the WA snapper and dhufish stock assessments do not show:

• raw CPUE time series

• standardised CPUE time series

• how far the two differ

• whether CPUE actually declined or simply flattened

The reader is asked to accept the conclusion without seeing the signal.

That is not transparency. That is faith.

CPUE standardisation methods and diagnostics

CPUE only works if fishing power and behaviour are stable or properly controlled.

Yet the WA snapper and dhufish stock assessments do not publish:

• the statistical model used to standardise CPUE

• which covariates were included or excluded

• whether vessel or fisher effects were applied

• how area and depth were handled

• diagnostics demonstrating robustness

Without diagnostics, CPUE can just as easily reflect:

• fleet contraction

• technological creep

• concentration into high-density areas

In demersal fisheries, CPUE is especially vulnerable to hyperstability. That risk is never addressed.

Post-release mortality assumptions

Both assessments fold post-release mortality into total fishing mortality.

But the WA snapper and dhufish stock assessments do not show:

• release rates by area and sector

• depth distributions of captures

• survival studies relevant to current practices

• sensitivity tests showing how results change if PRM is lower

If PRM is overstated, fishing mortality is overstated. If fishing mortality is overstated, stock status looks worse than reality.

Biological data is outdated

The WA snapper and dhufish stock assessments rely heavily on biological sampling that largely ends around 2017 to 2018.

What is missing:

• recent age structure

• recent recruitment strength

• sample sizes and spatial coverage

• area-specific biological signals

For long-lived species, this matters. Especially when management settings have already changed dramatically since then.

Spatial results are not shown

We are told recovery is uneven. Some areas worse, some better.

But the WA snapper and dhufish stock assessments do not show:

• biomass by area

• CPUE by area

• fishing mortality by area

• evidence of localised depletion versus whole-stock decline

Without spatial outputs, a problem in one zone can be used to justify blanket restrictions everywhere.

Uncertainty is hidden

Stock assessments live and die by uncertainty.

Yet these summaries do not show:

• confidence intervals

• credible ranges

• retrospective bias tests

• sensitivity to assumptions

A point estimate without uncertainty is not science. It is storytelling.

The question no one wants to ask

This is where the issue stops being academic.

At the same time these species are declared at risk, large-scale seismic testing has been approved in the same regions.

Seismic surveys involve intense, repeated, high-energy acoustic disturbance over vast areas. Yet their potential impacts are treated as secondary, minimal, or too uncertain to regulate.

So an uncomfortable question emerges:

If fish abundance is changing, why is fishing the only pressure being interrogated?

Why is fishing data scrutinised down to the decimal, while industrial acoustic disturbance proceeds on modelling assumptions?

Guesswork or something worse?

When:

• effort data is not shown

• CPUE methods are not disclosed

• uncertainty is hidden

• outdated biology is reused

• alternative pressures are ignored

The conclusions drawn by the WA snapper and dhufish stock assessments are not evidence-led.

At best, they are guesswork.

At worst, they are a convenient narrative that removes fishers while other industrial activities continue largely unchallenged.

This article does not claim intent.

But it does state plainly that intent becomes a reasonable question when transparency disappears.

What transparency would look like

If trust is the goal, the fix is straightforward:

• publish full effort and participation time series

• publish raw and standardised CPUE with diagnostics

• publish PRM assumptions and sensitivity

• publish spatial outputs

• publish uncertainty ranges

• explicitly address non-fishing pressures in the same footprint

Until that happens, claims made by the WA snapper and dhufish stock assessments remain assertions, not demonstrations.

And Australian fishers and seafood consumers deserve better than that.