Hopf et al. (2022; preprint online at Ecological Applications) investigated the issue of year-to-year variability in the larval recruitment of kelp forest fishes, and how it affects how we assess the effectiveness of marine protected areas for conserving those fishes. Using a 20-year dataset, we found that a common kelp forest fish in southern California has periodic peaks and troughs in recruitment, with a ~6 year cycle. Then, using age-structured population models we found that whether a new marine protected area was put in place during a peak or a trough either enhanced or delayed (respectively) post-protected population increases. That makes it more difficult to determine whether the reserve is successfully enhancing the population. Helpfully we also found that using before-after control-impact designs for monitoring helped mitigate this issue.

This project is a product of the Partnership for the Interdisciplinary Study of Coastal Oceans, and we hope it will inform the assessment of marine protected areas in California and Oregon in 2023.

Email will.white@oregonstate.edu if you would like a copy of the manuscript.

White et al. (2020, Conservation Letters: article press release) used a size-structured integral projection models to estimate harvest rates inside and outside of MPAs in California’s northern Channel Islands. The models were fit to length-based survey data collected by PISCO divers after the MPAs were established in 2003. The estimated harvest rates were effectively zero inside the MPAs (indicating no poaching) but much higher at some sites outside the MPAs, suggesting that perhaps fishing effort has been displaced from the MPAs to those sites.

This is the first example of using a population model to test for evidence of poaching in the population size structure itself, rather than using indirect assessments such as observations of fishing boats inside MPAs or game warden enforcement records.

These results, and the general approach, should be useful as California develops a state-wide assessment of its MPA network in 2022.

Pete Raimondi and Mark Carr (UC Santa Cruz) and I are hiring a postdoc to work on larval connectivity in marine protected area networks. Applications are due Dec 1. Contact me or Pete Raimondi with questions, but applications have to be submitted to Pete. Full ad here.

In December 2019, White lab members presented the final report on our work to understand spatial variability in oyster demographics and sustainability in the Guana Tolomato Matanzas National Estuarine Research Reserve (near St. Augustine, FL). The presentation was to the Oyster Water Quality Task Force, a group of local stakeholders comprised of harvesters, seafood workers, conservation workers, local governments, and interested citizens.

The final presentation can be found here.

Supplemental information for poster presented by Caren Barceló at the 2020 Ocean Sciences Meeting in San Diego, CA

Link to poster

Summary

We use age-structured population models to understand how fished populations respond to environmental variability. In general, fished populations exhibit greater variability than unfished populations, for two reasons: a) they are less dampened by density-dependent processes, and b) reproduction is concentrated into fewer ages, making it more likely that random events will ‘echo’ across generations. In this poster we share some preliminary analyses examining how no-take marine protected areas (MPAs) could reduce that variability by protecting part of the population from harvest. This is a potential example of how MPAs could provide resilience to environmental variability and climate change.

Follow us on Twitter! @barcelo_caren @kj_nickols @j_wilson_white

Related papers

Botsford LW, White JW, Hastings A. 2019. Population Dynamics for Conservation. Oxford University Press, Oxford, UK.

Nickols KJ, White JW, Malone D, Carr MH, Starr RM, Baskett ML, Hastings A, Botsford LW. 2019. Setting expectations for adaptive management of marine protected areas. Journal of Applied Ecology 56: 2376-2385

Botsford LW, Holland MD, Field JC, Hastings A. 2014. Cohort resonance: a significant component of fluctuations in recruitment, egg production, and catch of fished populations. ICES Journal of Marine Science 71: 2158-2170

Kaplan KA, Yamane L, Botsford LW, Baskett ML, Hastings A, Worden S, White JW. 2019. Setting expected timelines of fished population recovery for the adaptive management of a marine protected area network. Ecological Applications 29: e01949

White JW, Nickols KJ, Malone D, Carr MH, Starr RM, Cordoleani F, Baskett ML, Hastings A, Botsford LW. 2016. Methods for fitting state-space integral projection models to size-structured time series data to estimate unknown parameters. Ecological Applications 26: 2675-2692

Carr MH, White JW, Saarman EM, Lubchenco J, Milligan K, Caselle JE. 2019. Marine Protected Areas exemplify the evolution of science and policy. Oceanography 32:94-103. Special Issue on PISCO: Partnership for Interdisciplinary Study of Coastal Oceans

Easter EE, Adreani MS, Hamilton SL, Steele MS, Pang S, White JW. 2020. Influence of protogynous sex change on recovery of fish populations within marine protected areas. Ecological Applications, in press. DOI 10.1002/eap.2070

Botsford LW, White JW, Carr MH, Caselle JE. 2014. Marine protected areas in California, USA. In: Advances in Marine Biology: Marine Managed Areas and Fisheries, vol. 69. (Johnson ML and Sandell J, eds.). Elsevier, Oxford, UK, pp 203-249

White JW, Botsford LW, Hastings A, Baskett ML, Kaplan DM, Barnett LAK. 2013. Transient responses of fished populations to marine reserve establishment. Conservation Letters 6: 180-191

Supplemental information for the poster presented by Kerry Nickols at the Feb 2020 Ocean Sciences Meeting in San Diego, CA.

Link to poster

Summary

We use age- and size-structured population models to understand how fished populations respond to protection inside marine protected areas (MPAs). One generally expects population sizes to increase once fishing stops, but time lags due to demographics and year-to-year variation in larval recruitment can delay those increases. We present several examples of how population models can set expectations for detectable increases in fished populations will be detectable (and when they may never be detectable).

Follow us on Twitter! @kj_nickols @j_wilson_white

Related papers

Nickols KJ, White JW, Malone D, Carr MH, Starr RM, Baskett ML, Hastings A, Botsford LW. 2019. Setting expectations for adaptive management of marine protected areas. Journal of Applied Ecology 56: 2376-2385

Kaplan KA, Yamane L, Botsford LW, Baskett ML, Hastings A, Worden S, White JW. 2019. Setting expected timelines of fished population recovery for the adaptive management of a marine protected area network. Ecological Applications 29: e01949

White JW, Nickols KJ, Malone D, Carr MH, Starr RM, Cordoleani F, Baskett ML, Hastings A, Botsford LW. 2016. Methods for fitting state-space integral projection models to size-structured time series data to estimate unknown parameters. Ecological Applications 26: 2675-2692

Carr MH, White JW, Saarman EM, Lubchenco J, Milligan K, Caselle JE. 2019. Marine Protected Areas exemplify the evolution of science and policy. Oceanography 32:94-103. Special Issue on PISCO: Partnership for Interdisciplinary Study of Coastal Oceans

Easter EE, Adreani MS, Hamilton SL, Steele MS, Pang S, White JW. 2020. Influence of protogynous sex change on recovery of fish populations within marine protected areas. Ecological Applications, in press. DOI 10.1002/eap.2070

Botsford LW, White JW, Carr MH, Caselle JE. 2014. Marine protected areas in California, USA. In: Advances in Marine Biology: Marine Managed Areas and Fisheries, vol. 69. (Johnson ML and Sandell J, eds.). Elsevier, Oxford, UK, pp 203-249

White JW, Botsford LW, Hastings A, Baskett ML, Kaplan DM, Barnett LAK. 2013. Transient responses of fished populations to marine reserve establishment. Conservation Letters 6: 180-191

We are proud to have Nicole Peckham (Northeastern University PhD student) presenting a poster summarizing our NERR Science Collaborative Project at the 2019 Coastal and Estuarine Research Federation (CERF) meeting in Mobile, AL. This post has additional information about the project and the poster.

• Link to poster. “Stakeholder-driven modeling to understand oyster population sustainability.” J. W. White, L. Storch, N.E. Peckham, K. Dietz, D.L. Kimbro, N. Dix. This project is a collaboration with David Kimbro’s lab at Northeastern and the Guana Tolomato Matanzas NERR.

• The study system. The Guana Tolomato Matanzas National Estuarine Research Reserve is part of the nationwide NERR system. The GTM is an extensive estuarine system fed by multiple freshwater sources, and considerable spatial variability in tidal circulation, salinity, and oyster habitat. It supports both commercial and recreational harvest of oysters, but harvest is restricted to specific zones (see map on poster). The GTM NERR is a nexus for the Oyster Water Quality Task Force (OWQTF), a group of local harvesters, scientists, conservation workers, and interested members of the public. The OWQTF helps set research and management priorities for the GTM, and is a key end-user of the work.

This project was driven by questions arising in the OWQTF: what areas of the estuary support oyster reefs that contribute the most to population sustainability? What areas would be optimal for restoration (i.e., adding shell) or protection?

• Prior work. The Kimbro lab has been working in the GTM NERR since 2011, publishing studies on the role of increasing estuary salinity on oyster predators (Garland and Kimbro 2015) and fear-based interactions between oysters and their predators (Kimbro et al. 2014, Kimbro et al. 2017).

• Approach. Quantifying population sustainability fundamentally requires understanding the way individuals replace themselves via reproduction. However, lack of knowledge about the transport and connectivity of oyster larvae makes it impossible (at present) to describe the entire life cycle. Instead, we took an eggs-per-recruit (EPR) approach: if one new larval recruit settles in a site, how many eggs could it be expected to produce over its lifetime (on average)? Sites with higher EPR would be better suited for restoration (adding oyster shell substrate so that recruits can settle and survive) or protection (excluding harvest to promote larval production). More about this type of per-recruit analysis (and its history) can be found in Chapter 11 of our new book, Population Dynamics for Conservation.

• The model. We used a size-based integral projection model (IPM) to calculate EPR. An advantage of IPMs is that one can fit them to time series of size-abundance data to estimate unknown quantities, such as harvest rates (as opposed to age-based models, which can be harder to use because it is more difficult to age data from field surveys). Our group has published papers on fitting IPMs to time series to estimate parameters (White et al. 2016) and applying that approach to California oysters (Kimbro et al. 2019) and California marine protection areas (Nickols et al. 2019). The growth and mortality rates needed to parameterize the models were derived from field experiments conducted concurrently in our NSF-funded investigation of oyster predator-prey interactions in GTM NERR.

• Ongoing work. The results presented in this poster are preliminary; we are still working on additional analyses before the project ends. This will include a full population model, including reproduction and settlement, to investigate the effects of different harvest practices. Final model code will be made available in R for continued use by GTM NERR staff.

• Questions? Contact Will White.

A postdoc position is available in Dr. Lou Botsford’s lab at UC Davis, in collaboration with Alan Hastings (UC Davis) and Will White (Oregon State) This position will focus on the dynamics of fished populations inside marine protected areas, and interactions with fishery management. This 2-year position is funded by the California Ocean Protection Council. We seek candidates with strong quantitative skills in population ecology, fisheries, or spatial ecology. See details at link below. Applications should contact Lou Botsford at lwbotsford@ucdavis.edu. Full Position Announcement

We are currently recruiting a postdoc to work on population dynamics models for a project at the Guana Tolomato Matanzas NERR, funded by NERR Science Collaborative. This is a 12-month position with the potential for renewal. Ad & application information is here, please contact Dr. White with any questions!