Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis

Lok, Erica K.; Esler, Daniel; Takekawa, John Y.; Cruz, Susan E. W. De La; Boyd, W. Sean; Nysewander, David R.; Evenson, Joseph R.; Ward, David H.

doi:10.3354/meps09692

Cited by 31 publications

(29 citation statements)

References 41 publications

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“…A recent meta‐analysis on forage fish management and conservation worldwide recommends that existing uncertainties and knowledge gaps be explicitly addressed by adjusting conservation thresholds and harvest rates based on the quality and quantity of information on population status and key ecosystem linkages (Pikitch et al, ). Given the variability and uncertainty in Pacific herring egg loss rates (Figure ), a key parameter used to estimate herring populations, and the ecological importance of herring to higher order predators such as Steller sea lion, black bear, and sea ducks such as surf scoters (Anderson et al, ; Fox et al, , ; Lok et al, ; Willson & Womble, ; Womble et al, ), current conservation thresholds for Pacific herring (which equate to 25% of the estimated unfished biomass) need to be re‐evaluated in light of these global recommendations. Moreover, the uncertainty and variability in egg loss rates presented here have broad implications for uncertainty around reference points for forage fish management in general.…”

Section: Discussionmentioning

confidence: 99%

“…Along the northwest coast of North America, Pacific herring ( Clupea pallasii ) are a dominant species of forage fish that play a pivotal ecological role in pelagic and coastal foodwebs (Anderson, Lovvorn, Esler, Boyd, & Stick, ; Fox, El‐Sabaawi, Paquet, & Reimchen, ; Fox, Paquet, & Reimchen, ; Lok et al, ; Willson & Womble, ; Womble, Sigler, & Willson, ) and have significant cultural and socio‐economic value (Brown & Brown, ; O'Donnell et al, ). Archaeological and ethnographic evidence suggests that indigenous communities have harvested herring, in some places, for more than 10 000 years (McKechnie et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Each spring, from the low latitude coastlines of northern California, through British Columbia and northwards throughout Alaska, Pacific herring mass along the coast to spawn on benthic substrates (Haegele & Schweigert, ; Lok et al, ). Eggs are deposited on hard substrates and various species of marine vegetation, including low growing macroalgae and seagrass, as well as canopy forming kelps that occupy the water column (Fort, Daniel, & Thompson, ; Haegele, Humphreys, & Hourston, ; Haegele & Schweigert, ).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to these physical factors, predation by a variety of subtidal predators, as well as terrestrial predators that can access the intertidal, have been found to influence herring egg survival (Bishop & Green, ; Haegele, ; Haegele & Schweigert, ; Outram, ; Rooper, ; Willson & Womble, ). These community‐level interactions, from small beach‐associated amphipods (Fox et al, ) to migratory sea ducks (Lok et al, ) and top predator bears (Fox et al, ), demonstrate the pivotal connections that herring, their eggs, and the harvest of herring‐derived biomass play in the coastal environment. While these ecological linkages have been described, spatial variability in predatory effects and community‐level interactions have not been well resolved geographically.…”

Section: Introductionmentioning

confidence: 99%

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Factors driving spatial variation in egg survival of an ecologically and culturally important forage fish

Keeling

Hessing‐Lewis

Housty³

et al. 2017

Aquatic Conservation

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1. Low trophic-level forage fish are experiencing global declines, influencing coupled humanocean systems worldwide. Along the northwest coast of North America, declining trajectories of Pacific herring (Clupea pallasii) have prompted interest in improving the understanding of its population and community dynamics to better guide future conservation and management strategies.2. To improve future population estimates and understanding of the ecological factors governing herring egg survival, the magnitude, spatial variation and mechanisms driving herring egg loss rates were quantified. This was achieved by way of repeated observational field surveys and a predator exclusion experiment.3. Observational surveys revealed that regional egg loss rates (Z) were substantial and ranged from 0.101 ± 0.019 to 0.134 ± 0.028, the equivalent of 88-94% egg loss over a 21 day incubation period, or 50-60% egg loss over 6.8 days, the average time lag between spawn deposition and annual egg surveys. Furthermore, spatial variation was high, with egg loss rates varying 5-fold among study sites. Depth, time since spawn, and spawn area were primary spatial drivers of egg loss, but predator abundance and exposure were secondarily important. 4. Experimental evidence showed that benthic predation and habitat type were strong drivers of egg loss, suggesting that a high proportion of eggs, particularly those spawned on benthic substrates, are consumed by predators. 5. These results have important conservation implications for managers and ecologists seeking to estimate herring biomass and to understand the environmental influences on predator-prey interactions that affect herring dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Factors driving spatial variation in egg survival of an ecologically and culturally important forage fish

Keeling

Hessing‐Lewis

Housty³

et al. 2017

Aquatic Conservation

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“…Detected mortalities were given a fate of 0 (i.e., signal never disappeared) because the transmitter was retained up to the mortality event. We restricted our analysis to a period of 120 days from radio attachment, at which time scoters began to leave our study area for their spring staging grounds (Lok et al ).…”

Section: Methodsmentioning

confidence: 99%

Attaching transmitters to waterbirds using one versus two subcutaneous anchors: Retention and survival trade‐offs

et al. 2017

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A major challenge of wildlife telemetry is choosing an attachment technique that maximizes transmitter retention while minimizing negative side effects. For waterbirds, attachment of transmitters with subcutaneous anchors has been an effective and well-established technique, having been used on >40 species. This method was recently modified to include a second subcutaneous anchor, presumably increasing transmitter retention beyond that of single-anchor attachments. This putative benefit may be offset, however, by increased health risks related to additional incisions and subcutaneous protrusions. To test this potential trade-off, we attached radiotransmitters to molting and wintering surf (Melanitta perspicillata) and whitewinged scoters (M. fusca) during 2008 and 2009 in Washington State and southeast Alaska, USA, using single-(121 scoters) and double-anchor (128 scoters) attachment techniques. We estimated daily probabilities of survival and radio retention for each group, this being apparent retention for wintering scoters because we could not differentiate shed transmitters from flighted emigration. For scoters during the flightless remigial molt, we found that addition of a second anchor increased cumulative retention probability (AESE) over a 49-day period from 0.69 AE 0.11 for single-anchor to 0.88 AE 0.07 for double-anchor attachments, while having no effect on survival. However, during winter, scoters with double-anchor attachments experienced no improvement in apparent retention, while having significantly lower survival during their first 14 days following transmitter attachment; of 15 mortalities during this period, 11 had 2 subcutaneous anchors. From day 15 onward, winter survival rates were nearly identical for single-versus double-anchor attachments, indicating that adverse effects of subcutaneous anchors were mainly limited to the 14-day postattachment period. Overall, given that the survival cost of adding a second subcutaneous anchor was substantial for wintering scoters-decreasing 14-day survival by 12% for adults and 23% for juveniles-we recommend that researchers opt for single-anchor attachments under most circumstances, especially during winter when birds may be energetically challenged. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

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Application of lidar to assess the habitat selection of an endangered small mammal in an estuarine wetland environment

Hagani,

Takekawa,

Skalos

et al. 2024

Ecology and Evolution

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Light detection and ranging (lidar) has emerged as a valuable tool for examining the fine‐scale characteristics of vegetation. However, lidar is rarely used to examine coastal wetland vegetation or the habitat selection of small mammals. Extensive anthropogenic modification has threatened the endemic species in the estuarine wetlands of the California coast, such as the endangered salt marsh harvest mouse (Reithrodontomys raviventris; SMHM). A better understanding of SMHM habitat selection could help managers better protect this species. We assessed the ability of airborne topographic lidar imagery in measuring the vegetation structure of SMHM habitats in a coastal wetland with a narrow range of vegetation heights. We also aimed to better understand the role of vegetation structure in habitat selection at different spatial scales. Habitat selection was modeled from data compiled from 15 small mammal trapping grids collected in the highly urbanized San Francisco Estuary in California, USA. Analyses were conducted at three spatial scales: microhabitat (25 m2), mesohabitat (2025 m2), and macrohabitat (~10,000 m2). A suite of structural covariates was derived from raw lidar data to examine vegetation complexity. We found that adding structural covariates to conventional habitat selection variables significantly improved our models. At the microhabitat scale in managed wetlands, SMHM preferred areas with denser and shorter vegetation and selected for proximity to levees and taller vegetation in tidal wetlands. At the mesohabitat scale, SMHM were associated with a lower percentage of bare ground and with pickleweed (Salicornia pacifica) presence. All covariates were insignificant at the macrohabitat scale. Our results suggest that SMHM preferentially selected microhabitats with access to tidal refugia and mesohabitats with consistent food sources. Our findings showed that lidar can contribute to improving our understanding of habitat selection of wildlife in coastal wetlands and help to guide future conservation of an endangered species.

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Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis

Cited by 31 publications

References 41 publications

Factors driving spatial variation in egg survival of an ecologically and culturally important forage fish

Factors driving spatial variation in egg survival of an ecologically and culturally important forage fish

Attaching transmitters to waterbirds using one versus two subcutaneous anchors: Retention and survival trade‐offs

Application of lidar to assess the habitat selection of an endangered small mammal in an estuarine wetland environment

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