Better Mapping of Endangered Marine Species Using Local DNA and Net Captures

Jenn Hoskins
11th April, 2025

Better Mapping of Endangered Marine Species Using Local DNA and Net Captures

Atlantic Wolffish (Anarhichas lupus)

Photo adapted from: Viktor V. Grøtan / CC BY (Source)

Key Findings

  • In the Gulf of St. Lawrence, combining traditional trawl surveys with environmental DNA tests increased detection of endangered Atlantic wolffish from 13% to 23%
  • Environmental DNA reliably identified wolffish presence in all sampled cave habitats, providing a clearer picture of their distribution
  • Single-species DNA tests were more sensitive than multi-species methods, making eDNA a valuable tool for monitoring rare marine species
Monitoring the distribution of marine species is crucial for effective conservation and fisheries management. Traditional methods, such as trawl surveys, have long been the standard for assessing fish populations. However, these methods can be limited, especially when tracking rare or endangered species like the Atlantic wolffish (Anarhichas lupus)[1]. Fisheries and Oceans Canada conducted a study to evaluate the effectiveness of combining traditional trawl surveys with environmental DNA (eDNA) techniques to improve the detection and localization of this endangered species. Environmental DNA refers to genetic material obtained directly from environmental samples, such as water, without capturing the organisms themselves. This method has gained traction in recent years for its ability to detect a wide range of species, including those that are elusive or present in low numbers[2]. The study by Fisheries and Oceans Canada aimed to determine whether eDNA could complement trawl surveys in providing a more comprehensive understanding of the Atlantic wolffish’s distribution. In the study, researchers conducted fine-scale surveys using both trawl captures and eDNA detections across six stations. eDNA samples were collected using Niskin bottles over caves known to house one or two Atlantic wolffish. Additionally, samples were gathered with syringes by divers along a 15-meter transect perpendicular to each cave entrance. The findings revealed that eDNA was detected at all six stations sampled with Niskin bottles, indicating the presence of the wolffish within these habitats. In contrast, eDNA detections from syringe samples collected by divers were limited to the immediate vicinity of the cave entrances. When comparing the two methods, trawl captures alone identified the Atlantic wolffish at 13% of the stations. However, when eDNA detections were combined with trawl data, the frequency of species occurrence increased to 23%. This significant improvement suggests that eDNA can enhance traditional survey methods, particularly for rare species that may be underdetected by trawling alone. The study also differentiated between single-species and multi-species eDNA detections. Single-species detections were found to be more sensitive compared to multi-species detections. This sensitivity is crucial when monitoring endangered species, as it reduces the likelihood of missing their presence due to the complexity of the environmental DNA signals[3]. By focusing on single-species detections, researchers can achieve more accurate and reliable data on the distribution of target organisms. Integrating eDNA with traditional methods aligns with findings from previous research that highlights the strengths of combining molecular techniques with conventional approaches. For instance, a meta-analysis of DNA metabarcoding studies found that while DNA-based methods are consistent with traditional methods for fish communities, they offer additional insights into species diversity[3]. Similarly, the use of eDNA has been shown to correspond closely with acoustic-trawl estimates in large-scale surveys, demonstrating its potential for broad-scale applications in fisheries management[4]. Moreover, understanding the spatial dynamics of eDNA is essential for its effective application in marine environments. A prior study demonstrated that eDNA communities vary with distance from shore, and their similarity decreases as sampling sites become further apart[5]. This spatial consideration is relevant to the current study, as the localized detection of wolffish eDNA near cave entrances underscores the importance of sampling design in capturing accurate distribution patterns. The integration of eDNA into marine surveys offers several advantages. It provides a non-invasive means of monitoring species, reducing the need for physical captures that can stress or harm the organisms. Additionally, eDNA can detect species presence even when individuals are not directly observed, which is particularly beneficial for monitoring rare or cryptic species[2]. This capability is vital for conservation efforts, as it allows for more comprehensive and timely assessments of species populations and distributions. Fisheries and Oceans Canada’s study highlights the practical benefits of combining eDNA with traditional trawl surveys. By increasing the detection rate of the Atlantic wolffish from 13% to 23%, the study demonstrates that eDNA can fill gaps left by conventional methods. This approach not only enhances our understanding of species distribution but also supports more informed decision-making in fisheries management and conservation strategies. Furthermore, the study discusses strategies for optimizing eDNA detections in marine surveys. Effective integration requires careful consideration of sampling methods, replication, and spatial scale to ensure that eDNA signals accurately reflect the presence and abundance of target species[5]. By refining these strategies, researchers can maximize the utility of eDNA in various marine environments, thereby advancing the field of biological monitoring. In conclusion, the combination of traditional trawl surveys with eDNA analysis presents a promising advancement in marine ecology. For the Atlantic wolffish, an endangered species, this integrated approach offers a more reliable method for monitoring its distribution and abundance. As demonstrated by Fisheries and Oceans Canada, leveraging the strengths of both methods can lead to more effective and efficient biological assessments, ultimately contributing to the preservation of marine biodiversity in a changing climate[2][3][4][5].

EnvironmentGeneticsMarine Biology

References

Main Study

1) Improving an endangered marine species distribution using reliable and localized environmental DNA detections combined with trawl captures

Published 8th April, 2025

https://doi.org/10.1038/s41598-025-95358-3

Related Studies

2) Marine environmental DNA biomonitoring reveals seasonal patterns in biodiversity and identifies ecosystem responses to anomalous climatic events.

https://doi.org/10.1371/journal.pgen.1007943

3) Meta-analysis shows both congruence and complementarity of DNA and eDNA metabarcoding to traditional methods for biological community assessment.

https://doi.org/10.1111/mec.16364

4) Environmental DNA provides quantitative estimates of Pacific hake abundance and distribution in the open ocean.

https://doi.org/10.1098/rspb.2021.2613

5) Spatial distribution of environmental DNA in a nearshore marine habitat.

https://doi.org/10.7717/peerj.3044


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