12/10/2018
First of all, let me thank Dan Foster for giving us a bit of his for this session as well as for his continuous support for the project.
The goal of this session is to have an informal discussion on bycatch reduction technologies and take advantage of Dan's presence to review issues such as BRD construction, BRD testing and general approaches to reduce bycatch in bottom trawl fisheries.
This is also a good opportunity to ask Dan how the USA manages bycatch in it's bottom trawl fisheries and if there are any rules/practices that could be applicable in other countries.
Carlos Fuentevilla -REBYC-II LAC Project Coordinator
FAO - Food and Agriculture Organization of the United Nations
15/10/2018
Dear Dan,
I would be grateful if you could give us a note on your position with NOAA as well as a short background of your work with bycatch reduction in shrimp fisheries.
Carlos Fuentevilla
FAO - Food and Agriculture Organization of the United Nations
Hello Carlos,
I am a Research Fishery Biologist with NOAA. I have been with NOAA since 1984. I have conducted shrimp trawl bycatch mitigation research since 1990. I have been the shrimp trawl Bycatch Reduction Device (BRD) project lead for 12 years and have been the Harvesting Systems Unit Science Team Lead for 2 years.
Thank you for your question.
Dan Foster
NOAA
16/10/2018
Hi Dan Foster of NOAA and Carlos Fuentevilla of FAO, it is a pleasure to greet you and to share Costa Rica’s experience. It is quite comforting for me to say that once we’ve identified our bycatch we organized a roundtable with captains and net makers where –thanks to the training I received from NOAA- I was able to share my information and experience. Based on that we developed a new design and net constructions where we added elements such as a double footrope that gave us great results. Furthermore, we went from the 6inch Tico TED authorized in Costa Rica to the standard 4 inch flat bar TED. Lastly, we tested various BRDS such as fish eye with square mesh. We also designed a composite panel BRD with 6-inch mesh and on the inside, we placed a 1 ¾ in mesh funnel directing shrimp to the codend to prevent loss. I am proud to say that according to our data we have gone from 27kg of bycatch/ kg of shrimp to 1kg of bycatch/kg of shrimp. As such and based on this information, Costa Rica is already carrying out official technical studies so that we may comply with the orders from the Supreme Court. We hope that Costa Rica can soon reactivate its shrimp fishery.
Emanuel Gonzalez
CAMAPUN
Hello Emanuel,
It is great to hear from you. Thank you for sharing the results that you have obtained with the BRD development and testing that has taken place in Costa Rica. The results are indeed encouraging. In addition to the ratio of bycatch to shrimp, I would be very interested in seeing the average weight of shrimp caught in the control and experimental nets.
Dan Foster
NOAA
16/10/2018
I would like to ask if NOAA has any on-board sampling protocol that describes the methods and equipment to quickly and reliably determine weight differences between bags of nets that have generated catches.
I ask the question considering the atypical context of work on board of shrimp boats under commercial fishing conditions (stormy seas, crew working with limited time and wishing to process the catch as quickly as possible, an additional haul to the one already on the way. Besides, it is not always possible to install a scale on board to weigh the net bags directly before they are unloaded on the deck).
In case there is no written protocol, could you please describe how these situations have been resolved at NOAA? (minimum number of people generating data to properly process a fishing set, minimum required variables that they monitor, volume ratio and minimum number of shrimp samples and FAC for each bag).
José Alejandro Rodríguez Valencia
INAPESCA - México
Hello José,
Thank you for your good question. Gear testing on a commercial vessel is a very challenging undertaking and requires a highly skilled observer and very cooperative captains and crews. On some of our research vessels, we have scales that can weigh the catch in the bag before it is dumped. However, during our BRD testing on commercial fishing vessels we must weigh the catch after it is dumped on deck. The first challenge to working with the catch on deck is to make sure that the catches from the multiple nets are kept separate when dumped. The observer (with the help of the crew) must shovel the catch into baskets and weigh the baskets to obtain the total catch. The number of observers needed to sample catches during gear testing will be dependent on the fishery. In the Gulf of Mexico shrimp fishery, tows are generally 3-10 hour (depending on the season). We are able to conduct the gear testing with one highly trained observer and a cooperative crew. I have included some links to NOAA’s BRD Testing Manual and Observer Training Manual.
BRD Testing Manual
https://sero.nmfs.noaa.gov/sustainable_fisheries/gulf_fisheries/shrimp/brd/index.html
Commercial Shrimp and Reef Fish Observer Training Manual
https://www.galvestonlab.sefsc.noaa.gov/forms/observer/index.html
Sincerely,
Dan Foster
NOAA
16/10/2018
Thanks Carlos and Dan for setting up this forum, which is promoting the exchange of experiences.
Congratulations Emanuel for the achievements in Costa Rica. To go from a ratio of 27kg of bycatch / 1Kg of shrimp, to a ratio of 1Kg bycatch / 1 Kg of shrimp is impressive.
Is this a shallow shrimp fishery (10 fathoms)? or a deepwater shrimp fishery (20 - 30 fathoms)? I am asking because of the degree of ecological association at different depths.
When do you think that Costa Rica's results will be available to the public? I would like to know in detail the whole experience.
Lucas Pacheco
ARAP
Hello everybody, a pleasure to say hello again. I let you know that the research currently under way is taking place in the deep-water fishery for Farfantopeneus brevirostris, which is captured in depths of 30 to 120 m as well as the Solenocera Agassizi fishery that takes place between 150-400m. For us in Costa Rica, it has been very gratifying to share this experience with all and I hope that very soon. I can share the results.
Emanuel González Del Valle
CAMAPUN
17/10/2018
Thank you for this opportunity to seek clarification on the use of BRDs. In Trinidad in our last trial of the square mesh panel got 25% reduction in the relatively low catch season. We are modifying the gear to place the BRD further away from the bag tie in anticipation of bigger catches in the high season to mitigate possible shrimp losses and to see what the discard rate would be. My question is how does the US legislation address seasonal variation in the placement of these BRDs? Could we use the placement of the BRD in the low catch season as the standard for placing the BRD and legislate that all BRDs must be placed no closer than this specific number of meshes from the bag tie. I am thinking we would need a range in the trawl net for this placement of the BRD because in times of high catches the fishers could then move it forward as required but I am sure we don't want the BRD placed too close to the opening to make it ineffective. How does US regulations address this, if at all? Does the US have a range in the bag where the BRD could be placed? Also what would be a good research strategy to get these upper and lower placement limits for placement of the BRD?
Nerissa Lucky
Trinidad and Tobago's Fisheries Division
Thank you for your question. The southeastern US shrimp fishery regulations regarding BRDs do not address the seasonal variability in catch rates. We do recognize that there will be both seasonal and area variability in catch rates of target and bycatch species. However, it would be very challenging to attempt to adjust regulations to accommodate for these spatial or temporal variations. For the most common BRD used in the US, the fisheye, we allow the BRD to be placed a maximum of 9 ft from the bag tie-off rings. This configuration excludes an acceptable amount of bycatch while minimizing shrimp loss during the high volume times of the year. If the captain would like to place the fisheye closer to the catch during the low volume seasons (i.e. less than 9 ft), they are allowed to under the regulations, but it is not a requirement.
Dan Foster
NOAA
16/10/2018
Dear Dan, I also take this opportunity to request information (construction, installation, results, recommendations) about a BRD that was being tested on board the Caretta and that was developed by students. I honestly don’t remember the name but I saw it when I attended the NOAA training last year.
Emanuel Gonzalez Del Valle
CAMAPUN
Thank you for your question. I believe that the BRD you are referring to is the Nested Cylinder BRD developed by Dr. Glenn Parsons, a professor at the University of Mississippi. If you would like information on the BRD design and construction, you can contact him directly at [email protected]. The table below shows the results of a 30 tow trial.
|
Taxa
|
Mean CPUE Control
|
Mean CPUE MNCB
|
% Reduction
|
P
|
|
Wt. total catch
|
229.23
|
140.38
|
38.8
|
< 0.0001*
|
|
Wt. total finfish
|
196.77
|
112.89
|
42.6
|
< 0.0001*
|
|
Wt. total shrimp
|
11.73
|
11.51
|
1.9
|
0.3959
|
|
Wt. croaker
|
152.48
|
82.83
|
45.7
|
< 0.0001*
|
|
Wt. porgy
|
3.41
|
3.02
|
11.2
|
0.1015
|
|
No. red snapper
|
12.5
|
11.5
|
10.4
|
0.2153
|
|
Wt. red snapper
|
0.89
|
0.29
|
67.9
|
0.1621
|
|
Wt. finfish other
|
37.02
|
24.64
|
33.4
|
<0.0001*
|
* denotes significance at p< 0.05
Dan Foster
NOAA
17/10/2018
Given the global trend to ban bottom trawling of shrimp, I was wondering if the US has tried to pass a ban on the said fishery, and if so, how did it overcome the attempt and what role did NOAA or research institutes played through the development of BRDs in this process?
Daniela Kalikoski
FAO
Thank you for your question. While there has not been a direct attempt to ban trawling in the southeastern US shrimp fishery, there was a great deal of pressure placed on the fishery during the 1980s, when it was determined that the level of sea turtle mortalities occurring in the shrimp fishery was not sustainable. These finding prompted NOAA to develop mitigation measures to reduce sea turtle mortalities in shrimp trawls. These efforts resulted in the development and implementation of the turtle excluder device (TED). In the 1990s, NOAA developed and implemented bycatch reduction device (BRD) technology in the fishery to address a mandate to reduce bycatch in all fisheries to the extent practicable.
NOAA Fisheries tracks around 500 fish stocks managed by 46 fishery management plans. The stock assessments associated with the management plans take shrimp trawl bycatch into account and provide fishery managers with a scientific basis for setting sustainable harvest policies.
Dan Foster
NOAA
17/10/2018
Do you have a model of artisanal trawl net adaptable to boats of less than 10 meters in length with outboard motors, which has shown good results for the capture of shrimp, with a decrease in bycatch and including the location of the device fish escape (square mesh window) sizes of meshes and the rigging of the doors or of the method of dragging that it employs?
What stimuli can be implemented in the square mesh window to increase the rate at which fish escape through this device?
Juan Antonio Wong Lubo
INVEMAR-Colombia
Thank you for your question. We primarily work with larger vessels when researching bycatch reduction techniques. However, I suspect that many of the techniques developed for larger trawls will also apply to small trawls. We do have some net patterns for trawls designed for small boats. We also have a short video presentation of a typical southeastern US small boat trawling operation that we can provide. The choice of trawl design will depend on the species of shrimp that is being targeted. The netting size of the trawl and bag will depend on that size of the shrimp targeted. There is not a method to provide you with these materials on this forum. However, we will be happy to share this information with you directly.
Best regards,
Dan Foster
NOAA
18/10/2018
Hi Dan Foster and Carlos, thank you for setting up this forum. In Brazil, we are starting BRD tests with industrial double-rig shrimp trawl, and my doubt is about the round strap. In Brazil, trawl fisheries use the round strap to pull the net, unlike the fisheries in the Gulf of Mexico that already use the "elephant ears". We positioned the square mesh window in the initial portion of the codend. Would the fact that the square mesh window finish at the beginning of the round strap change its operation? And would this change be more related to bycatch or shrimp? Thank you.
Dárien Lucie Vernetti Duarte
CEPSUL/ICMBio
Thank you for your question. Since we don’t use the strap in our fishery, I don’t have much experience with how the strap will affect the BRD performance. However, we have conducted some tows recently with cameras mounted in the trawl to better understand how the strap affects the codend. We should have some video to share with the project countries soon. In all cases, the strap restricts the codend, almost completely during the tow. Therefore, the presence of the strap too close behind the square mesh window may result in shrimp loss. Either way, the positioning of the strap in relation to the BRD will be a critical consideration when evaluating the performance of the BRD for reducing bycatch and retaining shrimp.
Dan Foster
NOAA
19/10/2018
This question is related to the previous one by Derien Lucie Vernetti Duarte.
Hi just a comment on DerienLucie Vernetti Duarte question on the effect of a hauling strap on the function of a square mesh panel forward of the strap. I find that it is beneficial to tie the strap open with a piece of thin twine, this will break on hauling back. This will prevent the hauling rope from putting excessive pressure on the strap, and thus closing it.
Ian Kinsey
Ecofish consult
Thank you for the comment. I have not heard of the approach that you have mentioned. I suspect that it would work well at reducing the drag on the strap and help with the problem of the bag closing off. However, I do believe that changing to an elephant ear system would accomplish the same effect and would not require the twine to be attached before every drag.
Dan Foster
NOAA
18/10/2018
Hi Dan. By any chance, does NOAA have information on the hydrodynamic steel doors, results and benefits in shrimp fisheries?
Emanuel González Del Valle
CAMAPUN
We have not conducted research with hydrodynamic steel doors. There was an effort by a Sea Grant agent from Texas A&M University to get hydrodynamic steel doors introduced in the Gulf of Mexico around 10 years ago. However, the majority of the trawlers that used the doors have gone back to using the standard trawl doors. David Sterling, a researcher in Australia is an authority on the use of hydrodynamic doors in tropical shrimp fisheries. Steve Eayrs, who has co-authored some studies with him is also be a good contact for information on this topic.
Dan Foster
NOAA
18/10/2018
Good afternoon, considering that one way to reduce discards in the trawl fisheries is the reduction of bycatch through technological improvements, I think it is important for Latin American countries to know from NOAA and FAO, which technological devices such as GPS or others are being analysed for the detection in situ of shrimp species that allow to optimize the sets and thus reduce the accompanying fauna. This would be useful to, in the future, implement complementary projects for the use of state-of-the-art technology both in technological equipment and in the fishing gears that are being analyzed in the pilot sites within the REBYC LAC II project.
Eugenio Andrés Martin Botero
Ministerio de Ambiente y Desarrollo Sostenible (Colombia)
Thank you for your question. I am not aware of any research that is being conducted to evaluate the ability of sonar to detect shrimp on the bottom. My understanding of using sonar comes from personal experience and personal communication with shrimp vessel captains. I believe that it is difficult to detect shrimp on the bottom in the southeastern US with electronics due to the fact that the shrimp stay in close contact with the bottom. However, captains do use these electronics to detect and avoid areas of high bycatch. There are shrimp species that occur in other areas of the world that do form large aggregations off of the bottom where they can be seen by sonar and targeted. However, I am unaware if this occurs in the areas of the REBYC-II LAC project.
Best regards,
Dan Foster
NOAA
18/10/2018
Hello everyone, this forum seems very important and enriching, my question is located on the FAC, besides the studies on the decrease of the FAC in the shrimp trawl, have studies on diversity? What approaches have addressed?
Julia Ramos Miranda
Instituto EPOMEX, Universidad Autonoma de Campeche
Thank you for your question. In the southeastern US, we have trawl surveys and shrimp fishery observer programs to track population trends of the bycatch species that occur in the shrimp trawl fisheries.
Best regards,
Dan Foster
NOAA
19/10/2018
Thanks to Dan and FAO for this opportunity for the REBYC-II LAC project and all its participants. Dear Dan my question is related to aspects of data analysis to assess reductions of bycatch: Depending on the sampling design and given some restrictions related to the assumption of independence, ANOVAS are suitable tests for this type of comparisons? What other analyses can be applied? Is it possible to use resampling techniques (e.g. Boostrap, Monte Carlo), to generate data when, due to non-sampling situations, we can’t have sample sizes equal to 30 or higher? Thank you.
Mario Rueda
INVEMAR-Colombia
Thank you for the question. We typically use paired T test for analyzing our paired testing data. However, I have noticed and increase in the popularity of the randomization test. A safe approach to choosing a statistical analysis for your particular experimental design and sample size is to conduct a literature search of peer reviewed papers that have similar experimental designs to what you are doing.
Dan Foster
NOAA
19/10/2018
Dan, greetings from Costa Rica. With respect to the experiments we are doing in our country, it is important to note you can lower the amount of bycatch captured, if you use the appropriate net design. In the case of our country, the captains themselves designed a net in which, the first thing that was done was to lower the height of the net, which is logical, because the shrimp is down and is target fishing. Instead, with the previous height, it caught a lot of fish. On the other hand, with the double headline we managed to get several species, which do not jump like shrimp, to exit through the double space of the lower headline. The above, is in addition to the other attachments. Currently we are testing this design and others with bigger mesh sizes and as soon as we have results we will share them. Furthermore, your recommendations will be key, based on those results, because for next year we will carry out more experiments with other species.
Berny Marin
INCOPESCA - Costa Rica
Hello Costa Rica. I agree with you that reducing the height of the net can have the effect of reducing the catch of some semi-pelagic and pelagic bycatch species. In addition raising the footrope can reduce the bycatch of some demersal species. The effect of the raised footrope on the catch of shrimp will likely depend on the shrimp species, because the height that shrimp will jump off of the bottom is species dependent. As an example, in our fisheries we have two primary taxonomic groups (genus litopenaeus and farfantepenaeus). Litopenaeus spp. can jump very high off of the bottom and for this reason the height of the footrope is not as critical. However, the Farfantepenaeus spp. do not jump as high and the footrope should not be any more than 7-10 cm from the bottom when targeting these species.
Dan Foster
NOAA
19/10/2018
Dear Dan, could you comment on the impact of bycatch reduction devices on the volume of total production of target species and bycatch by the trawl fishing fleet in the Northern Gulf of Mexico?
Cecilia Quiroga
REBYC-II LAC National Coordinator Mexico
Thank you for your very good question. However, it is one that is difficult to answer. Since the BRD regulations went into effect around 1998, we have seen a dramatic decrease in the size of the fleet and as a result, a reduction of effort. The reduction in fleet size was due to the economic effects of fuel prices and shrimp imports, not the implementation of BRD requirements. While we did see a small decline in overall fleet landings, the vessel catch per day (CPUE) has more than doubled. With this dramatic change in vessel CPUE, it is difficult to detect what effect the BRD implementation may have had.
To address the second part of your question, prior to the implementation of BRDs in the Gulf of Mexico, observer data indicated that the finfish bycatch to shrimp ratio was approximately 4:1. Analysis of observer data after the implementation of BRDs indicate that the ratio of finfish to shrimp has dropped to 2:1. Analysis of survey data has also indicated that there has been an increase in biomass of some bycatch species in the gulf of Mexico.
Dan Foster
NOAA
28/12/2018
In reference to marine turtles and banning shrimp trawling in the Southeastern Region fisheries, when this issue arose back in the 1980’s, we had, at times, heated debates about the role of economics under the Endangered Species Act (ESA). Prior to turtle species being classified as threatened or protected under the ESA, a prolific fishery existed employing many fishermen and providing a broad array of products. When threatened or protected status was being considered over approximately, a five year regulatory process, turtle landings increased as their dockside prices rose because of expectations of a much limited supply in the future. When status was granted, harvesting for turtle species was banned and the fishery collapsed resulting in great costs being incurred. The protected status under the ESA essentially made turtle species a priceless commodity and its preservation was required regardless of the cost of doing so.
When a National Marine Fisheries Service biologist study of the Gulf of Mexico shrimp fishery discovered that 11 000 incidental turtle mortalities were occurring every year, a much more complex management problem developed. While banning shrimp trawling (as with the turtle fisheries) was perfectly legal under the ESA, less costly alternative approaches were suggested and adopted. A National Academy of Science study re-estimated turtle mortalities in the shrimp fishery at 44 000 per year, beach stranding surveys were undertaken and followed by regulations requiring 90 minute tow times by shrimp trawlers followed by voluntary TED and finally, mandatory TED use. Amendment 9 to the Gulf of Mexico Fishery Management Plan for Gulf of Mexico Shrimp Fishery reported that while TEDs were a major cost to the shrimp fishery, it was less costly than banning shrimp fishing altogether. Being less costly, TEDs were therefore a legal management regulation under the ESA. Although legal, its effectiveness has been under question. Beach stranding surveys in the 1990s seemed to suggest no change in mortality rates of turtles, head start programs and planting turtle eggs and juveniles on former nesting beaches did not report returns to their release sites after a decade. One successful project by shrimp fishermen in Brownsville, TX was their cooperation with Mexican authorities at Rancho Nuevo resulting in the recovery of the Kemps Ridley nesting beach, now reaching as far north as Padre Island, TX.
TEDs were later modified to reduce finfish bycatch in the shrimp fishery. These bycatch reduction devices (BRD) are still the preferred method to reduce finfish bycatch. A peer reviewed paper in the Journal of Marine Resource Economics used a bioeconomic simulation model to demonstrate that the long run equilibrium stock size of the bycatch species would not increase, even though the costs of fishing in the shrimp and bycatch fisheries had increased due to the adoption of the gear or by increasing fishing effort; respectively. A second paper published in the Journal of Business and Economics explored the dynamic oscillations in these fisheries on their path to the same long run equilibrium. Since these early papers, some thirty published studies have reaffirmed these results. In addition, Dr. Shannon L. Cass-Calay of the National Oceanic and Atmospheric Administration, Southeast Fisheries Science Center stated, in a public meeting of the Science and Statistical Committee of the Gulf of Mexico Fishery Management Council, that even with a 60% reduction in shrimp fishing effort (due to increased shrimp imports depressing the ex-vessel price of shrimp) the stock size of red snapper (a major bycatch species in the shrimp fishery) was not increasing after age 3 fish. However, an individual transferable quota regulation was adopted by the Gulf of Mexico Fishery Management Council that did give commercial fishermen an incentive to conserve red snapper that did lead to an improvement in stock size and resource rents. A recreational fishery that continued to fish as a regulated open access fishery saw their red snapper fishing season collapse to three days.
BRDs not so much a question of can it be done, as it is more a question of should we be doing it.
John Ward
Virginia Institute of Marine Science
23/10/2018
Hi Dan and Carlos,
It is very encouraging to see so much interest in this forum. Congratulations.
I noted an earlier discussion regarding the use of hydrodynamically efficient otter boards and reference to work by David Sterling and myself. First, David has done the bulk of this work and he continues to do so to this day. His most recent research has been with the “Batwing” board; a Google search will provide links to literature and images of this this unique and “extreme” design, which attempts to overcome the issue I mention below.
The key issue with so-called hydrodynamically efficient otter boards is they were designed primarily to be operated at low angles of attack, typically around 20 degrees. In shrimp fisheries the boards must be operated at 35 degrees or more to spread the trawl open during deployment and then over the seabed. However, at this angle the efficiency (life to drag ratio) of these boards is compromised and the hydrodynamic gains are seldom fully realised, although because they are still more efficient at these angles than a flat board, their overall size (and therefore weight) of the board can be reduced. I suspect the attraction of using a smaller, easier-to-handle board is one reason for their popularity, despite almost no gain hydrodynamically, although they are more expensive to purchase and repair, and arguably more challenging to rig and operate.
Now my question. Dan, I note in Costa Rica BRD performance is being measured using bycatch to shrimp ratios, and I am wondering if you know of any other fishery or country uses this metric to evaluate BRD performance? I am personally unaware of widespread use of this metric because it is so open to misinterpretation. For example, while a reduction from 27:1 to 1:1 seems very impressive, this means the BRD reduced bycatch by 97% per tow. A much better metric of course is average weight with confidence intervals (and preferably sample size), with all testing occurring at the same time and place on the one boat using identical fishing gear.
Regards.
Steve Eayrs
Smart Fishing Consulting
