Bait worms: a valuable and important fishery with implications for fisheries and conservation management

By Brenna Bales, SRC intern

Historically, bait fisheries around the world have been perceived as low-value, and their often limited, local extent makes large-scale management and conservation policy difficult to implement. Watson et. al 2016 explored three ragworm fisheries in the United Kingdom to investigate these claims, based on both evidence gathered scientifically and from an analysis of published literature. The data on polychaete bait fisheries is extremely limited, causing inaccurate estimates of catch amounts and collection efforts. In order to accurately assess the three bait fisheries of focus and other fisheries worldwide, Watson and other researchers assessed the following: retail value of bait species collected, extent of collection efforts both geographically and quantitatively, bait storage methods, and the choice and amount of bait used by angler fisherman on an average fishing trip.

The five most expensive (£/kg) species of marine animals sold on the global fish market are polychaetes (Glycera dibranciata, Diopatra aciculata, Nereis (Alitta) virens, Arenicola defodiens, and Marphysa sanguinea). The values of these bait species were quantified using retail prices of the species online and from data gathered from other literature sources. It was concluded that N. virens landings alone in the UK annually are worth approximately £52 million. Globally, this number is around £5.8 billion, with 121,000 tonnes of N. virens being landed worldwide. This demonstrates the high value of polychaete bait, contrary to popular opinion.

Nereis (Alitta) virens, commonly known as a sand worm, are a popular polychaete worm collected for bait purposes in UK tidal fisheries. (source: http://commons.wikimedia.org/wiki/File%3ANereis_virens_und_Nereis_diversicolor.jpg)

Nereis (Alitta) virens, commonly known as a sand worm, are a popular polychaete worm collected for bait purposes in UK tidal fisheries. (source: http://commons.wikimedia.org/wiki/File%3ANereis_virens_und_Nereis_diversicolor.jpg)

The three UK sites surveyed were Fareham Creek, Portsmouth Harbour; Dell Quay, Chichester Harbour; and Pagham Harbour. They were monitored over a period from August to September 2011, using remote closed circuit television recordings. The time for each digger on-site was recorded, and based on the number of times they placed a worm in their collection bucket, the biomass (mass of live worms) collected was estimated. The mean removal rate per bait collector per hour was 228 ± 64 worms. This large amount of collection can lead to things like environmental disturbance (trampling), over-exploitation of collection species, and the depletion of food resources for bird species that consume these worms.

This Japanese coastal bird feeds off a small ragworm, species that are globally collected as bait. When too many worms are removed by collectors, it can have serious consequences for the animals that rely on them for food. (source: https://commons.wikimedia.org/wiki/File%3ACharadrius_mongolus_stegmanni_eating_ragworm.JPG)

This Japanese coastal bird feeds off a small ragworm, species that are globally collected as bait. When too many worms are removed by collectors, it can have serious consequences for the animals that rely on them for food. (source: https://commons.wikimedia.org/wiki/File%3ACharadrius_mongolus_stegmanni_eating_ragworm.JPG)

An investigation as to how long certain species could be kept fresh before being used as bait on fishing trips was also conducted. The amount of time that N. virens could be maintained as viable bait was at the least 2 weeks. Given the average amount of N. virens used on angling trips per week was 0.33 kilograms, that amount of bait could be collected in only 28 minutes during a tidal cycle, based on the mean removal rate per bait collector per hour.

In conclusion, Watson et. al. proved that there needs to be a re-examination of the importance of polychaete bait fisheries worldwide, in order for better conservation initiatives to be launched. Seeing as the majority of these bait fisheries are located in MPAs (marine protected areas), better regulations must be enforced. There are several proposals in the study, such as personal catch limits, surveillance conservation, and stakeholder involvement. Overall, these fisheries are worth a lot more than is currently thought, and the implications of continuing poor management could have serious consequences.

Works Cited

Watson, Gordon J., et al. “Bait worms: a valuable and important fishery with implications for fisheries and conservation management.” Fish and Fisheries (2016).

A novel aspect of goby–shrimp symbiosis: gobies provide droppings in their burrows as vital food for their partner shrimps

By SRC intern, Andriana Fragola

The goby A. japonica and shrimp A. bellulus symbiosis are a perfect example of a mutualistic relationship between two marine animals. The goby lives in the shrimp’s burrow, which lends it shelter, and the goby warns the shrimp if there is a predatory threat nearby (Kohda et al. 2017). It has been hypothesized that the shrimp actually eats the goby’s droppings as its primary food source (Kohda et al. 2017). Kohda and colleagues conducted a laboratory experiment to replicate this relationship, and examine if this feeding behavior is actually occurring.

Figure1 

Field studies were conducted to examine the goby and shrimp interactive behavior. Between the shrimps, A. bellulus and the gobies A. japonica it was observed that the shrimps were not foraging much outside of their burrow, and the gobies were never really observed defecating outside of their burrow (Kohda et al. 2017). Most burrowing organisms do not defecate inside of their burrows – likely to be an act to keep it cleaner (Kohda et al. 2017). If the shrimp is using the goby’s droppings as a nutritional supplementation, then it would not be an issue of keeping the burrow clean because the droppings would still be removed via consumption by the shrimp (Kohda et al. 2017). The animals were collected at Morote Beach, Ehime Prefecture, Japan and were then studied in a laboratory setting.

The gobies and shrimps were kept in tanks with the burrow being a vinyl tube with one open side up against the glass wall of the tank for visual observation (Kohda et al. 2017). This experiment took place over a 2 week period. The shrimp were weighed prior to and after the experiment to determine if they had lost weight when they had no access to food other than the goby droppings (Kohda et al. 2017). In treatment 1, in order to make the goby feed inaccessible to the shrimp, it was placed on a suspended board away from the entrances of the burrows (Kohda et al. 2017). This way the goby could reach the food by swimming, but the shrimp could not and had to rely entirely on the goby droppings for nutrition. In treatment 2, the gobies and shrimp were kept in different tanks, and the researchers collected the goby faeces and then placed them up at the top of the shrimp’s burrow (Kohda et al. 2017). The shrimps were noted to come to the entrance and collect the faeces and bring them back down into the burrow and eat them (Kohda et al. 2017). A control tank was set up where the shrimp were isolated from the gobies, and were not fed during the entirety of the experiment (Kohda et al. 2017).

Final observations noted that the gobies stayed very close to the burrow unless they were feeding, and were never observed defecating outside of the burrow (Kohda et al. 2017). The shrimp were never noted to forage outside of the burrow unless they were taking algae off of the rocks near the burrow entrance (Kohda et al. 2017). Between the two treatments, there was not a significant difference between body weight of shrimps prior and after the experiment (Kohda et al. 2017). But there was a significant decrease in shrimp body weight in the control groups where they were isolated from the gobies (Kohda et al. 2017). Meaning that the shrimp were able to maintain a stable body weight with only the goby faeces as food (Kohda et al. 2017).

 

Figure2
Understanding behavioral relationships between species is incredibly important for conservation initiatives. Learning that two species heavily rely on each other to thrive is vital in establishing protection for them. In a mutualistic relationship similar to this, both species need to be protected because if one is missing, they cannot perform their usual behaviors, and do not have that resources they typically rely on. For example, the droppings of the goby being a primary food source by the shrimp. This study demonstrated that solely having goby droppings as food is enough to maintain the shrimp’s weight even without other nutritional sources available (Kohda et al. 2017). Therefore the goby is a very beneficial to the shrimp as a partner, and without these mutualistic relationship the shrimp would have a much more limited food supply, and the goby would not have a burrow to reside in.

Works cited
Kohda, M., Yamanouchi, H., Hirata, T., Satoh, S., & Ota, K. (2017). A novel aspect of goby–shrimp symbiosis: gobies provide droppings in their burrows as vital food for their partner shrimps. Marine Biology, 164(1). doi:10.1007/s00227-016-3060-2

Use of local ecological knowledge to investigate endangered baleen whale recovery in the Falkland Islands

By SRC intern, Molly Rickles

In this study, Frans and Auge looked at baleen whale population in the Falkland Islands in the post-whaling era. Due to whaling in the early 1900s, whale populations here have decreased dramatically, but recent observations suggest that their numbers are currently increasing. However, there is a lack of population data, making this study critical.

Methods

The main goal of the research was to understand how well the baleen whale population is doing post-whaling in the Falkland Islands. To do this, the scientists used LEK, or local ecological knowledge. In this method, interviews were conducted with local Falkland residents to determine how often whales are sighted off the coast. The residents were asked to draw pictures on a map of where they saw the whales. Each interview was given a reliability rating based on how confident and detailed the account was. This data was used to supplement the existing International Whaling Committee data from the whaling era. With the combined data, the researchers aimed to look at when the whale sightings were most common and to determine the most common places where the whales were seen.

SRC pic 1

Results

Over the course of the study, 3,842 whale sightings were recorded and Falkland residents recorded 631 of those observations. Since LEK is not always a reliable method, it was determined that about 70% of the observations recorded using LEK were reliable, and could be used in the study. It was found that in the 1970’s, no whale sightings were recorded because it was right after the whaling era. By the early 2000’s, the number of whale sightings increased 11-fold, showing a population recovery. Out of all of the baleen whale species, sei whales (Balaenoptera borealis) showed the largest increase since the whaling era, and are currently the most abundant whale species in the Falkland Islands. It was also determined that baleen whales are most common during the summer and fall months, based on recorded sightings.

Outcomes

This study was an important step in understanding baleen whale populations and how they have recovered since the whaling era. Using LEK allowed the scientists to get population data even when there was a lack of empirical data, which is a new technique that hasn’t been used regularly in other studies. This new technique allowed the researchers to determine baleen whale populations in the Falkland Islands, which can be used as a reference for the future of whale conservation. This is especially critical now because of the increasing threats to whales, such as increasing economic development in the Falkland Islands. Since the whales have recovered from the whaling era, it is now important to keep the population healthy, and this study provides an important monitoring tool for future conservation efforts.

SRC pic 2

References

Frans, V.F., & Auge, A. A. (2016). Use of local ecological knowledge to investigate endangered baleen whale recovery in the Falkland Islands. Biological Conservation, 202, 127-137. dio: 10.1016/j.biocon.2016.08.017

Decorating behavior begins immediately after metamorphosis in the decorator crab Oregonia gracilis

By Nicolas Lubitz, SRC intern

Invertebrates, animals without a backbone, are the oldest form of animals that exist on our planet. The first fossils of invertebrates date back to 665 million years ago, and are sponges. Since then, they have diversified into a spectacular array of organisms, both marine and terrestrial. From insects, to squids and corals, to jellyfish, their forms and shapes seem to know no limits. Some studies suggest that invertebrates make up 97% of all animal life on the face of the earth. For example, coral reefs provide shelter and structures for other organisms, most invertebrates are prey for higher organisms, but many invertebrates are predators themselves, like squid. With no doubt those creatures are vital to our marine and terrestrial ecosystems, and understanding their biology helps us to ultimately understand how every part of an ecosystem revolves around another part.

Figure 1. Invertebrate diversity (http://www.deepseanews.com/2011/11/octopi-wall-street/)

Figure 1. Invertebrate diversity (http://www.deepseanews.com/2011/11/octopi-wall-street/)

Because of the fantastic diversity of tasks they perform conserving invertebrate diversity is important to ocean health. Steven R. Hein and Molly W. Jacobs from the University of Washington and Miami University, respectively, have shown that there is even more to consider when looking at marine invertebrates. In their recent paper they looked at the decorator crab Oregonia gracilis (figure 1). Decorator crabs are known to use debris and other organisms such as sponges and algae to cover their outer layer, most likely for camouflage and protection. Just like other invertebrates of the order crustacea (which includes crabs and lobsters) decorator crabs go through different stages in their lives from larvae, to an intermediate phase, the so called megalopa, to a juvenile phase to the final adult stage. Each phase is very different in appearance and behavior. Hein and Jacobs were interested in how those different life stages utilize different habitats and different forms of debris and organisms to decorate themselves and how.

The decorator crab, Oregonia gracilis (http://www.crabs.ru/russia/fam_oregoniidae_oregonia_gracilis.htm)

Figure 2. The decorator crab, Oregonia gracilis (http://www.crabs.ru/russia/fam_oregoniidae_oregonia_gracilis.htm)

In order to do so, they collected and bred different life stages of this particular decorator crab species and provided them with different decorating materials and habitats and compared the different stages for preferences. The results are clear: Although the early megalopa phases were found in mostly the same habitat as the juvenile phase, they did not decorate themselves at all. Juveniles, on the other side, utilized free floating organic debris to cover themselves which in turn is very different from adult individuals who use algae, sponges and other organisms. According to the researchers, the different body shapes of megalopae, juveniles, and adults requires all phases to adapt to different niches in order to survive.

When we look back to our idea of conservation we realize that when trying to come up with regulations and protective measurements for such organisms we should understand every single life stage of this particular organisms in order to ensure their conservation and protection. Hein and Jacobs indirectly demonstrated that laying out conservation measurements for just the adult phase appears to be insufficient since the whole life cycle has to be taken into consideration. Here we see that conservation is an integrative field and includes many components that we must look at for conserving our oceans.

Reference

Hein, S.R. & Jacobs, M.W. (2016) Decorating behavior begins immediately after metamorphosis in the decorator crab Oregonia gracilis. Marine Ecology Progress Series, 555, 141–150.

Sea Bird Telomeres

By Dave Lestino, SRC intern
Telomeres are located at the ends of each DNA strand. They can be thought of as the plastic tips of shoelaces, and protect the chromosome from deterioration. Although telomeres can’t measure exact chronological age, they can be used to measure individual quality. Use of telomere length, as a quality marker, is increasing as seen in handful of studies between 2004 and 2015. In most species, it has been observed that telomeres shorten overtime, and length corresponds with survival, life-span and reproductive success. In a study by Young et al. in 2016, telomere lengths were compared to quality markers, such as environmental condition, in the thick-billed murre.

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Methods
Young et al. assessed individual quality through parental investment behaviors (trip rate and nest attendance), body condition and physiological stress (baseline corticosterone or CORT). Their samples came from three colonies of thick-billed murre (Uria lomvia), which is a species of long-lived seabird. They sampled 97 individuals from 3 colonies (Bogoslof, St. George and St. Paul) in the Baring Sea, each living under different environmental conditions. The colony on Bogoslof had easy access to nearby food sources, while St. George had access to distant but reliable sources and St. Paul had access to nearby but unreliable food sources. These food sources relate to good, intermediate and poor environmental conditions comparatively.

Young chose this species because murres are known to adjust time budgets as conditions in the environment change, in order to offer consistent levels of parental investment. Thus, telomere length would indicate quality indicators and not age as the underlying driver of telomere length. The authors predicted that longer telomere length would be associated with low baseline CORT, high body condition and high parental investment. They also predicted poor environmental conditions should strengthen the above relationships. Chick rearing murres were captured, weighed, sampled for blood and fitted with Cefas G5 loggers to record time, temperature and depth pressure every 2 seconds. After 3 days the birds were recaptured and skeletal measures were taken. In total 101 birds were captured, but due to some sampling errors the final analysis consisted of 97 individuals.
For telomere length and baseline CORT assays were completed on the blood samples. Parental investment was based on nest attendance and rate of foraging trips. To calculate nest attendance, they looked at what proportion of total time was spent at the colony, measured by a Cefas loggers mounted on the birds, recording temperature and depth. Temperatures reading higher than air or sea indicate incubation, while changes in incubation temperature marked the beginning and end of a foraging trip. Trip rate was then determined by dividing the number of trips by the total deployment time. Response variables (CORT, body condition, trip rate and attendance) were analyzed with linear models in the R environmental statistic program.

Results
The results showed that under good environmental conditions CORT was higher in birds with shorter telomeres. In poor conditions however, this was not strengthened as predicted but instead was reversed. Birds with longer telomeres had higher levels of stress. This implies that under stressful conditions, such as the poor environment at St. Paul, younger birds will be stressed even with high individual quality. Older more experienced birds however can maintain moderate stress levels. Predictions that telomere length could predict parental investment were incorrect. A paper by Elliott et al. in 2015 shows that parental behaviors don’t change with age. Murres have shown to change foraging strategies depending on distance to food sources. The interaction of sex and colony for explaining attendance patterns can be seen in Fig. 3. In conclusion, the authors found that telomere length relates to stress levels with environmental factors acting as important mediators. As habitats around the world decline, these findings can hopefully help in futures studies to determine individual quality of species in degraded areas

References
Young RC, Barger CP, Dorresteijn I, Haussmann MF, Kitaysky AS (2016) Telomere length and environmental conditions predict stress levels but not parental investment in a long-lived seabird. 556, 251–259.

A Scientific History of Oysters in Chesapeake Bay

By Nicole Suren, SRC intern

Oysters are not only a preferred dish of much of the human population, but they are also very important parts of the ecosystems they inhabit. As ecosystem engineers, or organisms that significantly modify their habitat, they do not just participate in the habitat they settle in but improve it by filtering large volumes of water and forming reefs that other organisms can use as shelter. Unfortunately, the estuary systems that they prefer have been in steep decline for some time due to negative effects of human activity, and scientists are currently attempting to quantify how much these ecosystems have declined by examining the average sizes of oyster populations over time. Here, Rick et al. (2016) focused on Chesapeake Bay in the northeastern United States.

Oyster Paper, Figure 1

Change in oyster size over time

There is an important relationship between the size of the oysters and how healthy their populations are. Generally speaking, larger average oyster size correlates with a healthier and more abundant oyster population. With this in mind, scientists examined fossilized oysters ranging from 1,500-3,000 years ago, oysters from Native American archaeological sites, and modern oysters to see how the introduction of humans and later new fishing technologies would affect the oyster populations. They found that the prehistoric oysters were the largest, and that the introduction of harvesting by Native American populations did not affect the average size of the oysters. However, the introduction of new fishing technology resulted in an increase in oyster size, but this then decreased to a much smaller average size than the prehistoric samples today.

Measurements of Chesapeake Bay oysters taken by NOAA

Measurements of Chesapeake Bay oysters taken by NOAA

What do these changes mean?

Several things about these results are important. First, the increase in oyster size upon the advent of new fishing technology can be attributed to people having access to parts of the oyster population that they had not had access to previously. The Native Americans were believed to harvest oysters by hand, so this would have limited them to slightly smaller oysters in shallow waters. In contrast, new fishing techniques such as trawling would have harvested the larger oysters in deeper waters, so the size increase is likely due to a difference in sample areas between the two time periods. Second, since there was no size difference between the oyster populations before and after Native American settlement in Chesapeake Bay, it can be concluded that the Native American oyster fishery was very sustainable. This is hypothesized to be due to their aforementioned harvesting methods, low population density, broad-spectrum diets (that are not completely dependent on oysters), and lack of a significant oyster trade.

Implications for current management

While it would be impossible to fully emulate the sustainability of the Native Americans of that time, we can use the same principles to modify our own activities to make the modern oyster fishery more sustainable. For example, fishing limits on larger oysters in deeper waters, decreased harvests of all oysters, and restoration techniques can be implemented, all of which mirror Native American sustainability strategies in a modern world. The implications of this study show that science is deeply rooted in cultural phenomena, and can incorporate the best of culture and sustainability to better the planet.

Oyster Paper, Figure 2

Reference
Rick TC, Reeder-Myers LA, Hofman CA et al. (2016) Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery. Proceedings of the National Academy of Sciences, 113, 6568–6573.