Policy Perspectives From archives to conservation: why historical data are needed to set baselines for marine animals and ecosystems Loren McClenachan1,2, Francesco Ferretti3, & Julia K. Baum4 1Department of Biology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada 2Environmental Studies Program, Colby College, Waterville, ME 04901, USA 3Hopkins Marine Station, Stanford University, 120 Oceanview Blvd., Pacific Grove, CA 93950, USA 4Department of Biology, University of Victoria, Victoria, BC V8W 2Y2 British Columbia, Canada Keywords Endangered species fisheries management marine turtles overfishing restoration sharks shifting baselines. Correspondence Loren McClenachan, Department of Biology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada. Tel: 858.405.9512 Fax: 778.782.3496. E-mail: loren.mcclenachan@gmail.com Received 16 December 2011 Accepted 19 April 2012 Editor Rich Zabel doi: 10.1111/j.1755-263X.2012.00253.x Abstract Intergenerational loss of information about the abundance of exploited species can lead to shifting baselines, which have direct consequences for how species and ecosystems are managed. Historical data provide a means of regaining that information, but they still are not commonly applied in marine conservation and management. Omission of relevant historical information typically results in assessments of conservation status that are more optimistic, recovery targets that are lower, and fisheries quotas that are higher than if long-term data were considered. Here, we review data and methods that can be used to estimate his- torical baselines for marine species including bony fishes, sharks, turtles, and mammals, demonstrate how baselines used in management change when his- torical data are included, and provide specific examples of how data from the past can be applied in management and conservation including extinction risk assessment, recovery target setting, and management of data-poor fisheries. Incorporating historical data into conservation and management frameworks presents challenges, but the alternative���losing information on past population sizes and ecological variability���represents a greater risk to effective manage- ment of marine species and ecosystems. Introduction A growing number of marine ecologists and fisheries scientists has recognized long-term human impacts on marine species and ecosystems, and developed new ana- lytical methods to incorporate historical data into assess- ments of change (e.g., Jackson et al. 2001 Lotze & Worm 2009). These studies have revealed substantial changes in marine fish, turtle, and mammal populations, pro- viding baselines against which modern populations can be benchmarked (Pauly 1995). Yet while the relevance of these baselines to conservation and management has been noted (e.g., Samhouri et al. 2011), in practice, agen- cies and organizations concerned with long-term trends in the abundance of marine animals rarely use historical data. Relevant data from the past are often overlooked or discarded in extinction risk assessments, recovery tar- get setting, and fisheries management (e.g., Prefontaine 2009). By contrast, terrestrial ecosystem management more commonly employs data from the past, including paleoecological data (e.g., fossil pollen and tree rings) to identify invasive species and wildfire regimes (Willis & Birks 2006), and historical data (e.g., written narratives, photographs, and land surveys) to identify reference con- ditions for forest restoration (Moore et al. 1999). The historical exploitation of marine animals, which has influenced their modern abundances, typically oc- curred over shorter timescales than are recorded by ma- rine sediments and fossils, but longer than are captured by modern ecological observations, so that neither ade- quately reflects anthropogenic impacts. Information from the past several decades to centuries���the recent past��� is particularly relevant for long-lived, exploited species, such as marine turtles, mammals, and slow growing Conservation Letters 0 (2012) 1���11 Copyright and Photocopying: c 2012 Wiley Periodicals, Inc. 1

From archives to conservation L. McClenachan et al. fishes. Here, we show how relevant historical data can be gathered and analyzed for a range of marine species and ecosystems, demonstrate that the omission of these data can lead to significantly different outcomes than when they are included, and outline specific conservation and marine management frameworks that would benefit from the inclusion historical data. Recent historical data: challenges and revelations Historical data relevant for understanding human impacts on marine animal populations and ecosystems include narrative and archival documents, early survey and mon- itoring records, interviews with fishers and other resource users, and recent zooarchaeological remains (Figure 1, Table 1). While these data are nontraditional in marine science, disciplines including history, geography, and an- thropology rely on them, and have established protocols for their collection and use. When interpreted in an eco- logical context, such data can be used to estimate quanti- tative baselines for historically exploited marine animals and to provide perspective on past ecosystem states (Lotze et al. 2011a Table 1). Information from structured inter- views with fishers in the Gulf of California (n = 108), for example, provided evidence that maximum daily catches of Gulf grouper (Mycteroperca jordani) declined by a factor of 25 over the past 60 years (r2 = 0.62, P 0.001) (Saenz- Arroyo et al. 2005). Spatially explicit daily catch records from the 1850s for Atlantic cod (Gadus morhua) were val- idated with ancillary historical records and integrated into traditional fisheries models to estimate that cod biomass on the Scotian Shelf in 1852 was 1.26 million metric tonnes (mt), 25 times larger than at present (Rosenberg et al. 2005). Zooarchaeological remains and spatially explicit descriptions of the Caribbean monk seal (Monachus tropi- calis) were modeled with biological parameters from ex- tant species to estimate that 13 breeding populations were eliminated between 1700 and 1952 (McClenachan & Cooper 2008). Methods to analyze historical data include meta-analysis of trends derived from multiple sources (e.g., Branch et al. 2004 Ferretti et al. 2008), ���then and now��� comparisons of past and modern abundance infor- mation, catch statistics, and trade records (Baum & Myers 2004 Lotze & Milewski 2004 Saenz-Arroyo et al. 2005 Rosenberg et al. 2005 McClenachan et al. 2006), and spa- tial analyses based on georeferenced data from past re- source users and early naturalists (Ames 2004 Lotze & Milewski 2004 McClenachan & Cooper 2008). Despite advances in historical data collection and anal- yses of long-term changes in abundances and distribu- tions of marine animals, historical data are not commonly incorporated into existing conservation and management contexts, for several reasons. Historical data are difficult to collect they may be in a variety of languages, only accessible in small archives for which no metadata or electronic resources exist, or buried in documents cre- ated for a different purpose. Furthermore, the challenge of integrating unfamiliar data sets, such as narrative ac- counts and trade records, into established quantitative modeling frameworks or standardized assessment proto- cols presents a barrier to their use, as does the fact that data from the past are often imprecise and are therefore not valued as highly as recent monitoring data. Finally, funding barriers exist: management agencies do not typi- cally have the resources to develop new expertise to con- duct historical research. When historical data are included in marine popula- tion status assessments they frequently reveal more dras- tic declines than can be seen with short-term observa- tions alone (Figure 2). The long-lived and historically exploited green turtle (Chelonia mydas) provides an ex- ample of how the duration of data significantly affects assessments of population change. Green turtles were hunted globally for centuries historical sources describe tens of thousands of turtles killed for local consumption and export markets, with extirpation of nesting beaches and severe population declines (McClenachan et al. 2006 Table 1). Where historical data ( 100 years) on the abun- dance of nesting females on specific nesting beaches are available, ���then and now��� comparisons reflect these de- clines, estimating a population reduction of 80%. In contrast, similar comparisons in locations where data are only available over periods of 30 years show net popu- lation increases approaching 30% (Figure 2A data from Seminoff 2004). Hawksbill turtle (Eretmochelys imbricata) populations provide an even more striking example. Intensive hunt- ing of hawksbill turtles for tortoiseshell had severe effects on populations (McClenachan et al. 2006): when ���then and now��� comparisons of nesting females are made with data spanning 52���107 years, they reflect near extirpa- tion, with average declines of 91%. In contrast, similar comparisons using data from the past 8���31 years show populations to be increasing, at an average of 333% over the span of the data. Increases exceeded 700% over 20 years for one breeding population, an implausible fig- ure for the population dynamics of this long-lived species (Figure 2B data from Mortimer & Donnelly 2008). In the most recent International Union for the Conserva- tion of Nature (IUCN) Red List assessment, qualitative and semiquantitative data from sources including 19th century customs records and natural history descriptions were used to validate the long-term trends derived from historical nesting data, demonstrating that while localized 2 Conservation Letters 0 (2012) 1���11 Copyright and Photocopying: c 2012 Wiley Periodicals, Inc.