Imagine walking into a bar where the walls are lined with photographs of fishermen showing off their trophy catches. You might first notice the unmistakable, or even regrettable, fashions of the decades from which they were taken, as well as the enormity of the prized fish caught. But to some scientists’s eyes, these photos are more than just a time warp; they hold important ecological data.

Dr. Loren McClenachan is a historical ecologist who thinks creatively about how to fill gaps in our understanding of ecosystems and species abundances through time. She uses historical data in the form of photographs as well as maps, nautical charts, exploitation and trade documents, newspaper articles, logbooks, catch reports, and oral histories to travel into the past and view information that would otherwise be all but lost.

Types of historical data available through time. McClenachan et al. (2015)

The core principle of historical ecology is that “understanding present biotic conditions requires viewing them through the lens of past interactions with human societies” (McClenachan et al. 2015). By considering data that extends further back in time, we can obtain a more panoramic picture rather than just a snapshot from today. Dr. McClenachan uses “then and now” comparisons between historical and modern ecological data, with a goal to inform current management and conservation decisions.

Trophy fish caught on Key West charter boats: (top to bottom) 1957, early 1980s, 2007. (Photos: Monroe County Public Library and McClenachan)

A picture is worth a thousand words data points

Dr. McClenachan used photographs taken between 1956 and 1985 to document the loss of the large trophy fish in the Florida Keys, and compared them with photographs that she took in 2007. She found a major shift in species composition across reef communities through time, with larger predatory fish being fished first, followed by a steep decline in the sizes and weights of fish caught more recently. Historically, catches were dominated by large sharks and goliath groupers, but today, the catches are almost exclusively small snappers. Interestingly, Dr. McClenachan found that the cost of fishing trips did not decrease, meaning customers paid approximately the same price for a ~20 kg trophy fish as they do for a ~2 kg trophy fish now, some 50 years later.


A case of shifting baseline syndrome: where did all the fish go?

The loss of top predators in the Florida Keys stems from chronic overfishing of the most desired, or largest fish, and Dr. McClenachan’s work is a pivotal example of shifting baselines. Shifting baseline syndrome is a measure of the ecosystem at a point in time that becomes the new normal, or as Dr. Daniel Pauly explains: “each generation of fisheries scientists accepts as a baseline the stock size and species composition that occurred at the beginning of their careers, and uses this to evaluate changes” (Pauly 1995).

People will continue to fish while marine ecosystems undergo extreme changes in community structure
Dr. Loren McClenachan

If the motivation of trophy fishing is to be out on the water, beer in hand and catching fish, then maybe relative size or cost is irrelevant. But without historical context, how would we know otherwise? It is hard to deny the feelings that these trophy fish photographs evoke, reminiscent of a time when our marine ecosystems were in a better state. Dr. McClenachan’s novel research shows how history can inspire and motivate our conservation of marine ecosystems, and can even benefit users.

Key West trophy fish, 1956. (Photo: Monroe County Public Library)

A little history in marine historical ecology

The discipline of marine historical ecology continues to grow, and is important for animals that have been significantly exploited over short periods of time. For example, Kittinger et al. (2011) used catch landings and restaurant menus to consider the depletion of green turtles in Hawaii, once thought to have been attributed to tourism. This study revealed that the abundance of green turtles was depleted prior to the major tourism influx to the Hawaiian Islands, and was caused by increasing fishing pressure due to local market demand. SAFS’ very own Dr. Trevor Branch employed logbook records to establish baseline data for Antarctic blue whales (Branch et al. 2004). He showed that while the population had been increasing since 1974,  the current abundance was still below 1% of pre-exploitation levels and that protections should remain.

Interdisciplinary uses for historical data

Dr. McClenachan’s use of historical data serves as another excellent example of the value of interdisciplinary work, a consistent theme of this year’s Bevan Series. The integration of social science and traditional science can provide greater context to our conservation and management efforts, and has the potential to expand the reach beyond our field. The importance of historical data is clear: losing information about past populations and natural ecological variability is a risk to current marine ecosystems and protections for them into the future. 
It might never to be possible to find all the necessary source documents and fill in all of the data gaps, but use of best practices shows that historical findings often produce surprising results that provide important insights on past population trends and the ability to develop hypotheses for future research (McClenachan et al. 2015).

All good things take time, and historical ecology is no exception. Dr. McClenachan invests in learning about each unique ecosystem before determining what story it might tell. She does not set out to answer specific questions immediately, instead she is inspired by what data is available.

You may never look at photographs of trophy fish in a bar as you did before — we certainly won’t. We hope that Dr. McClenachan’s research makes you, the beholder, see photographs of fisherpeople with their trophy fish and wonder about what historical data lies within. There might just be a story waiting to be told.

References & Further Reading

Branch, T.A., Matsuoka, K., and Miyashita, T. 2004. Evidence for increases in Antarctic blue whales based on Bayesian modelling. Mar. Mammal Sci., 20, 726–754.

Kittinger, J.N., Pandolfi, J.M., Blodgett, J.H., Hunt, T.L., Jiang, H., Maly, K., McClenachan, L., Schultz, J.K., and Wilcox, B.A. 2011. Historical reconstruction reveals recovery in Hawaiian coral reefs. PLOS ONE 6 (art.e25460).

McClenachan, L. 2009. “Documenting Loss of Large Trophy Fish from the Florida Keys with  Historical Photographs.” Conservation Biology, vol. 23, no. 3, 2009, pp. 636–643., doi:10.1111/j.1523-1739.2008.01152.x.

McClenachan, L., Ferretti, F., Baum, J.K. 2012. From archives to conservation: Why historical data are needed to set baselines for marine animals and ecosystems. Conservation Letters 5: 349–359.

McClenachan, L., Cooper, A.B., McKenzie, M.G., Drew, J.A. 2015. The Importance of Surprising Results and Best Practices in Historical Ecology. BioScience, 65, 9:932-939

Pauly, D. 1995. Anecdotes and the shifting baseline syndrome of fisheries. Trends in Ecology and Evolution 10: 430