Deriving robust historical population trends for long-lived species subject to human exploitation is challenging in scenarios where long-term scientific data are scarce or unavailable, as often occurs for species affected by small-scale fisheries and subsistence hunting. The importance of Local Ecological Knowledge (LEK) in data-poor scenarios is increasingly recognized in conservation, both in terms of uncovering historical trends and for engaging community stewardship of historic information. Building on previous work in marine historical ecology and local ecological knowledge, we propose a mixed socio-ecological framework to reliably document and quantify LEK to reconstruct historical population trends. Our method can be adapted by interdisciplinary teams to study various long-lived taxa with a history of human use. We demonstrate the validity of our approach by reconstructing long-term abundance data for the heavily-exploited East Pacific green turtle (Chelonia mydas) in Baja California, Mexico, which was driven to near extinction by a largely unregulated fishery from the early 1950s to the 1980s. No scientific baseline abundance data were available for this time-frame because recent biological surveys started in 1995 after all green turtle fisheries in the area were closed. To fill this data gap, we documented LEK among local fishers using ethnographic methods and obtained verified, qualitative data to understand the socio-environmental complexity of the green turtle fishery. We then established an iterative framework to synthesize and quantify LEK using generalized linear models (GLMs) and nonlinear regression (NLR) to generate a standardized, LEK-derived catch-per-unit-effort (CPUE) time-series. CPUE is an index of abundance that is compatible with contemporary scientific survey data. We confirmed the accuracy of LEK-derived CPUE estimates via comparisons with fisheries statistics available for 1962–1982. We then modeled LEK-derived abundance trends prior to 1995 using NLR. Our model established baseline abundance and described historical declines, revealing that the most critical (exponential) decline occurred between 1960 and 1980. This robust integration of LEK data with ecological science is of critical value for conservation and management, as it contributes to a holistic view of a species’ historic and contemporary conservation status.

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The rate of production of leaf biomass in eelgrass (Zostera marina L.) is an indicator variable for environmental influences on the growth of this important seagrass species. The efforts to restore eelgrass meadows from the harmful human influences make the use of nondestructive evaluations essential. We present, here, an indirect procedure for the estimation of the growth rates of eelgrass leaves by using easily obtained measurements of leaf length and increases in leaf length, and allometric parameters linked to the scaling of leaf biomass and leaf length. This allometric method includes criteria that allow the estimation of leaf growth rates even when the sizes of some of the leaves cannot be determined because of herbivory or other environmental factors. To validate the proposed method, we performed simulation studies and analyzed data from two natural eelgrass populations in the East Pacific (México). These allometric projections of leaf growth rates displayed a high level of correspondence with observed values. We show that whenever the allometric parameters for the scaling of eelgrass leaf dry weight in terms of leaf length have been previously fitted, the method proposed here can provide an alternative for estimating biomass production that is both accurate and nondestructive and uses easily obtained data on leaf length and increases in leaf length between the sampling periods.

ABSTRACT. Restoration of eelgrass Zostera marina meadows from harmful anthropogenic influences has made it essential to evaluate these efforts by using non-destructive assessments. Allometric methods provide a convenient framework for the derivation of reliable indirect assessments of leaf biomass and leaf growth of eelgrass. Invariance of the involved parameters could grant truly nondestructive assessments because previously fitted values could be used to produce consistent estimations. In order to explore this property we analyzed data from two natural eelgrass populations in the East Pacific (México), as well as populations in the West Pacific (two natural in Korea and one mesocosm in Japan). When we compared observed leaf growth rates with those projected allometrically by using parameter values fitted at different sites, we found that only parameter values fitted at sites within the same geographical region can produce consistent results. Therefore if this restriction holds previously fitted parameters can indeed be used to produce reliable non-destructive assessments of eelgrass leaf growth rates. Keywords: Zostera marina, foliar growth, eelgrass meadow, allometric modeling, restoration evaluation.Efectos de la variabilidad paramétrica en la obtención de tasas de crecimiento foliar en Zostera marina L. mediante métodos alométricos RESUMEN. La restauración de praderas de Zostera marina que han sido dañadas por influencia antropogénica, ha hecho necesaria la evaluación de estos esfuerzos mediante métodos no destructivos. Las metodologías alométricas proporcionan un marco formal que favorece la obtención de estimaciones indirectas de biomasa y tasas de crecimiento foliar. La invariancia de los parámetros asociados asegura la obtención de técnicas de estimación no destructiva de gran confiabilidad, puesto que, parámetros previamente ajustados podrían usarse para producir estimaciones consistentes. Para investigar la existencia de esta propiedad se analizan datos provenientes de dos poblaciones naturales de Z. marina en el Pacífico oriental (México) así como también poblaciones en el Pacífico occidental (dos naturales en Corea y una cultivada en laboratorio en Japón). Al comparar valores observados de tasas de crecimiento foliar con aquellos obtenidos alométricamente, utilizando parámetros ajustados en sitios indistintos, se observó que únicamente cuando los parámetros provienen de una región geográfica equivalente se pueden producir resultados consistentes. Por lo tanto, tomando en cuenta esta restricción parámetros alométricos previamente ajustados pueden, en efecto, producir evaluaciones no destructivas y fiables de tasas de crecimiento de las hojas de Z. marina.