Operations Guide for the Recovery of Derelict Crab Pots from Shallow Soft Sediment Estuaries: Lessons Learned from a Mid-Atlantic Coastal Bay

Transcription

1 Operations Guide for the Recovery of Derelict Crab Pots from Shallow Soft Sediment Estuaries: Lessons Learned from a Mid-Atlantic Coastal Bay This project was funded by the NOAA Restoration Center, Office for Habitat Conservation NOAA Grant #NA12NMF CFDA# Richard Stockton College of New Jersey Dr. Mark Sullivan mark.sullivan@stockton.edu, PI School of Natural Science and Mathematics Dr. Peter Straub peter.straub@stockton.edu, co-pi 101 Vera King Farris Drive Steve Evert steve.evert@stockton.edu, co-pi Galloway, NJ Jacques Cousteau National Estuarine Research Reserve 130 Great Bay Blvd. Tuckerton, NJ Melanie Reding reding@marine.rutgers.edu, co-pi

2 1.0 Introduction Recovering derelict Chesapeake-style crab pot gear (ghost pots) from shallow soft-sediment estuaries presents particular challenges due to the sedimentation depth of the gear and the relatively thin wire mesh of which they are constructed. In estuaries where fishing activity occurs in depths less than 15 storm events that create surface waves of a few feet or more create a vibrating effect on bottom gear that will cause the gear to move down into the soft sediment. In the Mullica River-Great Bay estuary researchers and commercial waterman recovered over 1000 pots. Over 50% of those pots were 8 or more into the sediment and created difficulty in removals. Using grapple hook gear for the recovery of ghost pots is an effective means of recovery, especially when combined with the use of low-cost sonars to put recovery teams within 20 of the lost gear. However, waterman and researchers in this shallow water/soft sediment estuary found that excessive use of force resulted in torn wire mesh and frustrating pullouts. Techniques developed in this project found that large anchor-style grapple hooks, once secured in a ghost pot and brought up tight to the recovery vessel provided the most effective means of pulling that pot from the bay floor without tearing through the thin wire mesh. Once pulled from the bottom, pots then need to be towed in a circular direction until a reasonable amount of the sediment is removed. Ghost pots that are 8 or more into the sediment weigh over 100 lbs. if that sediment is not removed via the towing method. This document is intended to be used in conjunction with the DVD Recovering Lost Crab Traps: New Jersey s Community Approach, to provide commercial waterman and other recovery teams with the basic skills required to recover ghost pots from estuaries where fishing activity is in relatively shallow water and soft sediments are typical. The DVD is available by contacting any of the authors or by visiting the website wecrabnj.org. It is important to note that the use of a low cost sonar system is not only an effective tool for the recovery of ghost pots in a restoration effort but also during the active crabbing season and immediately following the discovery of a lost pot. Waterman in this project now use their low cost sonar systems to recovery their gear, and their catch, immediately following the discovery that their surface buoy has been cut. Over the 2013 and 2014 crabbing season MRGB waterman recovered over 85% of their lost gear in the days immediately following the cut-off event, savings themselves thousands of dollars each.

3 2.0 Low cost sonars Low cost, or recreational-grade side scan sonars have been on the market for over 10 years now, with many advancements in their ease of use, effectiveness, and now with multiple manufacturers offering quality units at costs as low as $1000. Side scan sonar uses an acoustic signal, just like that of a typical depth sounder or fish finder, but in a side-looking fashion, essentially showing the user what is lying on the bay floor to the sides of the vessels track and in some cases out to 75 or more. Metal and manmade targets show up particularly well, and crab pots make for an easily recognizable target. In this document we cover the use of a Humminbird side scan sonar unit. It is important to note that there are multiple manufacturers that provide waterman and recovery teams with instrument options, and the basic operational procedures are quite similar. You should consult your local marine electronics dealer for low cost side scan sonar options.

4 3.0 Retrieval methods The methods outlined below all share one common need the operator must see the target on the sonar and use one of the marking methods. Low cost sonars are very effective at seeing ghost pots up to 40 on either side of the boat in waters less than 20 deep. Once a fisherman or recovery team has used a sonar for a few days they become fairly easy to recongize from other types of debris, depending on conditions and other factors.

5 3.1 Retrieval tools Retrieval tools are simple and can be made form readily available materials. Options for snagging the target range from multiple small grapple hooks in line on wieghted 100 ropes to items as simple as a 10 lb. grapple anchor attached to a length of line relative to the water depth (4x anticipated recovery water depth). 3.2 Marking the location with a surface buoy This method is used in either restoration recoveries or during in-season recoveries by waterman. It is especially effective when working in areas of high ghost pot density. 1. Have a weighted buoy line set to only a few feet more than the anticipated water depth and ready to throw at a moment s notice 2. Set sonar to a range of (either side of the boat) 3. Cover an area until an obvious crab pot is seen within about 20 of the vessel s track line 4. Using the transducer location as your reference, throw the buoy to the area where the target was seen, accounting for forward motion 5. Circle back and travel directly next to the buoy, noting the direction and distance from the buoy to the ghost pot 6. Prepare for recovery

6 3.3 Marking the location with the GPS plotter for later recovery This method can be used by restoration teams that use a low cost sonar to survey or by waterman during the season when they do not have time that day to recover a lost pot. Some advanced users of plotter/ side scan units can also use this method to recover without the aid of a surface buoy. 1. When a desired target is seen on the imaging screen immediately move the cursor a. This freezes the image screen 2. Once the cursor is over the target, press and hold the MARK button 3. Write down the waypoint number for future reference 3.4 See, toss and snag with multiple grapple system This method involves seeing the target, tossing a surface buoy, and recovering the target via the multiple grapple or single grapple systems. Multiple grapple hook systems are pictured in section 3.1 and are generally deployed from the target and drug around the target in a circle. Once snagged, the operator can pull back until they are over top of the snagged pot and can throw an additional grapple anchor into it. Follow common retrieval methods for pulling from the sediment. 3.5 See and snag with single grapple anchors This method can be used in calm conditions with an experienced recovery team or waterman. Mark the target using the surface buoy method and then follow these steps. 1. Go by the surface buoy and note distance and direction to the target 2. Two grapple hooks anchors on heavy lines (length = 4x water depth) cleated off to the transom of the boat 3. Go as close as possible to the target, preferably directly over it ( split the pot ) 4. Once seen, pull the boat out of gear and point to the pot location, throw or have deckhands throw grapples 5. Once connected to the target, come up one side of the boat and cleat off to a forward cleat. 6. Follow retrieval methods to pull from sediment.

7 7. Ideally with this method you can split the pot (see below), meaning the transducer went directly over it and you can toss the grapple hook right behind it, snagging it most times. 3.6 Pulling a Ghost Pot from soft sediment Ghost pots in soft sediment-dominated estuaries are often silted in, where the pot is actually buried in the sediment anywhere from a few inches to two feet. This presents retrieval challenges that are unique to these small coastal bays (vs. deeper waters or sand/gravel dominated systems). Once a grapple system of any type is into a pot it will either stop the boat or tear the mesh. Using larger vessels and greater pulling force results in torn mesh and failed recoveries. 1. Operate your small vessel at idle speeds when deploying grapple gear 2. Once gear grabs a ghost pot immediately pull the vessel out of gear a. Use wind and tide forces as necessary to keep line taught b. Pull up tight to the pot and tie off the grapple gear short to a forward or midship cleat c. If possible, put second large grapple in the pot by hand-tossing 3. Be aware of pulling forces and the potential for capsizing a boat tied off to a ghost pot a. Put the vessel into a shallow inboard turn, straightening and turning slightly with minor throttle adjustments b. The pot will pull from the sediment c. Continue in a circular fashion, increasing speed d. Straighten boat a bit and look or use a boat hook to find the pot s long line (there 80% of the time) e. Grab that line and you will not lose that pot if the mesh rips 4. Once the majority of the sediment is removed, pull the ghost pot aboard and follow any recording procedures

8 3.7 More information The authors of this document, with the help of their local waterman and women, developed these recovery techniques to be successful in shallow bays typical of the Mid-Atlantic region. Larger and deeper estuarine systems and those where sediment structure is typically consolidated sands, gravels and even rock, may have opportunities to pull ghost pots with larger vessels and heavy hauling gear without tearing the thin wire mesh of a commercial blue claw crab pot. However, shallow water retrievals of Chesapeake-style commercial crab traps require smaller vessels with drafts less than 30, and techniques geared toward removing intact pots that may be 4 24 into a soft, muddy bottom. This group of New Jersey researchers and commercial fisherman are interested in helping you start a recovery program in your area, or if you re a commercial waterman helping you learn the techniques to recover lost gear immediately, saving you possibly thousands of dollars per year if you lose more than 20 pots in a typical season. Commonly asked Questions? How do I know if my system has a problem? Talk with commercial fisherman, assuring them that you are interesting in heling the resources, the ecosystem, and them! Assess boat traffic areas versus heavily fished areas of the two coincide you likely have some significant level of ghost pots. How do I get started? Call us, we ll be happy to talk with you about your system and possible opportunities. We will send you an informational DVD and other training resources and if possible arrange a visit for your team to our site for a demonstration. What do we need? You need manpower, small vessels and knowledgeable operators, a low cost sonar system and a grapple recovery system. What other training materials are available? We have several documents and computer-based presentations available in addition to the DVD that will be sent to you free of charge while supplies last (thanks NOAA!). ================================================================================================ Retrieving ghost crab pot gear from shallow estuaries typical of the Mid-Atlantic is difficult work. The benefits however can be far-reaching through both the ecosystem services that the removals provide and the decrease in navigational hazards in your shallow bay. The additional benefits to the commercial fishing community through the return of fishable gear or recycle parts, and the prevention of further lost gear through are rewarding, as are the community partnerships that these projects can foster. For more information please contact the authors and also visit our website at Additional thanks to the following commercial crabbers in the Mullica River- Great Bay system: Phil Andersen, Al Kurtz, George Leeds, Karen and Warren Unkert Additional thanks to the following contributors: Kirk Havens et. al. (project star-up advice), Mr. Vince Capone (sonar training), Nate Robinson (sonar and field ops), Elizabeth Zimmermann (photos, video and dockside help), and many volunteers from Stockton College and the JC NERR