Competing Hypotheses and Scientific Non-Recognition: Investigating the Hector’s and Māui Dolphin Decline in the Context of Wartime Chemical Legacies

Abstract

This e-poster examines the decline of Hector’s and Māui dolphins in New Zealand as a case of fragmented ecological knowledge and competing causal explanations. It does not argue that herbicide-related contamination caused the decline. Instead, it explores how competing hypotheses should be evaluated when evidence is incomplete, unevenly distributed, and institutionally sensitive.

The dominant explanation emphasizes fishing-related mortality, including bycatch and net entanglement. An alternative hypothesis considers possible exposure to organochlorine contaminants, including dioxins, furans, PCBs, DDT-related compounds, and residues associated with chlorinated herbicides linked to the wider Vietnam War-era chemical production economy.

The central issue is methodological rather than causal. Different hypotheses may receive unequal scientific attention under conditions of incomplete evidence. Drawing on the concept of regimes of scientific recognition, the poster examines how evidence is selected, connected, excluded, or downgraded when explanations are politically, institutionally, or scientifically inconvenient.

The poster proposes a comparative framework that evaluates fishing, demographic fragility, habitat change, and contamination-related hypotheses according to available evidence, explanatory power, and remaining uncertainties. Its contribution is methodological: to promote fair and transparent testing of competing explanations when ecological evidence is fragmented and causation remains contested.