A novel approach for directly incorporating disease into fish stock assessment: a case study with seroprevalence data

Abstract

When estimating mortality from disease with fish population models, common disease surveillance data such as infection prevalence are not always informative, especially for fast-acting diseases that may go unobserved in infrequently sampled populations. In these cases, seroprevalence — the proportion of fish with measurable antibody levels in their blood — may be more informative. In cases of life-long immunity, seroprevalence data require less frequent sampling intervals than infection prevalence data and can reflect the cumulative exposure history of fish. We simulation tested the usefulness of seroprevalence data in an age-structured fish stock assessment model using viral hemorrhagic septicemia virus (VHSV) in Pacific herring (Clupea pallasii) as a case study. We developed a novel epidemiological model to simulate population dynamics and seroprevalence data and fitted to these data in an integrated catch-at-age model with equations that estimate age- and time-varying mortality from disease. We found that simulated seroprevalence data can provide accurate estimates of infection history and disease-associated mortality. Importantly, even models that misspecified nonstationary processes in background or disease-associated mortality, but included seroprevalence data, accurately estimated annual infection and population abundance.

The role of diseases in unifying the health of global estuaries

“…Further, the initial increase was largely driven by review and experimental studies with a subsequent wave of increases due to observational and modeling studies. This may have been motivated by the new literature being generated for marinebased diseases, which can use published data for parameterization and interpretation (Hoenig et al, 2017;Trochta et al, 2022). Finally, our data show that studies do not often make the connection between pathogen dynamics and keystone species.…”