Observations from the Albatross IV  correctional cruise

Cap't. Jim  Lovgren



Link to fisheries survey information
Follow this link to other background
information on fisheries research:

(Note that diagrams and specifications of the sampling net used in the surveys and this cruise are available at http://www.nefsc.noaa.gov/femad/ecosurvey/mainpage/survey_gear.htm)
 
 Five New England fishermen and myself met at Woods Hole Ma. On the evening of Tuesday, Sept. 24, 2002, to board the N.O.A.A.  research Vessel

Albatross IV. The other fishermen were Jim  Odlin, Sam Novello, Bud Fernandes, Matt Stommel, and Steve Lee. We  met with Steve Murawski, [ who did not go out on the trip] and with Henry Milliken, and Russell  Brown  who were in charge of  reviewing the fishing and filming of this short cruise. Individually we walked around the vessel and checked out the net and gear. As I was the last fisherman to arrive, the gear , [Which was laying on the deck] had already been closely scrutinized by the other fishermen, and some  problems had been identified.  Matt Stommel, who is the fisherman that had been saying that the cables were not properly measured since he saw them being put on in 2000, noticed that one door was wearing differently then the other, meaning that the gear probably was not spreading properly. This observation was later reinforced    by our observations underwater with the video camera. The camera, was mounted in the center of the top line [head rope] but  whenever  we had the camera facing dead center backwards, [towards the codend], the  bottom sweep would be off center towards the starboard side.  As these doors [Portuguese Polyvalent], are rarely used anymore, and werenít very common even when they were new, most of us had little first hand experience in using them, but we thought that the problem was probably being caused by excessive wear in the door  brackets. As the doors are probably the single most important component of a properly tuned  otter trawl rig, having one door not working properly can have a major effect on catch rate, as the spread of the net can be affected.

Two other observations were made about the net as it lay on the deck.  Upon casual notice it appeared that the cookie sweep on one wing appeared to be newer then the other. Closer observation confirmed that one wingís sweep had been  replaced   as there were definitely new cookies on one sweep, and old worn ones on the other.  The worst aspect of this wing change was  that by visual observation  it was plainly clear that the  new wing had more cookies on it then the other wing. Upon measuring  the wings and comparing them, the wire rope sweep which is threaded through each individual cookie  were both  the same length , 22 and a half feet. But there were 16 inches more cookies at the wing end of the port wing, [new sweep side]. I would bet that if each cookie sweep was removed from the net and individually weighted that the new sweep would weight considerably more then the old sweep, even if they were the same length, due to the wear and tear placed on the old cookies as they scraped  and bounced  along various bottom types. Also noticeable  by casual observation was that the  roller chains [droppers]   were not attached  to the sweep at the standardized spacing of  2 feet, some were less, we didnít measure and count these but we probably should have. Absolutely, there is no question  that one wing was not the same as the other. The second thing was  noticed once again by Matt,  who since he lives in Woods  Hole is very familiar with this net. Matt claims that the foot rope used to be tied to the  wire rope traveler in the space  between each length of roller chain. 

The foot rope is now tied to the  3 inch rings at the end of  each roller chain. This would be  in our opinion another change that would affect the catch rate of the net, as the twine would behave a little differently then before.  In a 8 page paper on the specifications for construction of N.E.F.S.C. standard  #36 bottom  survey trawl [ 601-801]  that was given to us so that we could see the nets exact specifications,  you can see from a diagram of the net on page 4 that the footrope was formerly tied to the traveler, it appears that this diagram is dated 10/27/00 which means that the change to the footrope was probably made since then. The reason a change was made is also referenced in this paper on page 3 in the paragraph for seizings.  The footrope is seized to the pear shaped rings that are used to attach the droppers [roller chains] to the sweep. The traveler passes through the pear shaped rings that the footrope is seized to. 

This eliminates the problem of the seizings slipping and bunching of the footropeĒ.  This 8 page paper states that it was updated on 8/12/2002, the need for the update was probably to note this change in the way the footrope was hung, they forgot to update the net diagram though and that clearly shows the  footrope tied to the traveler.  In my opinion the change in how they hung the footrope was probably a good change in that it would reduce maintenance of the net, as the seizings would not slip and the net would hold its shape better. But how this change would affect the nets performance is unknown and could be substantial either for better or worse.

These observations that, as noted, were made before we even left the dock point out very serious discrepancies in the centerís supposed standardization procedures, where we have been told over and over again that changes could not be made in the survey or to the net because their effect could not be substantiated.  These changes, repairs, and unnoticed problems by themselves would have some effect on the nets performance, cumulatively their effect could be enormous.

We left the dock and steamed  during the night to one of the sampling stationís on the fall survey. A  few tows were made during the night, I donít know whether it was two or three as I went to bed, since the camera tows were going to be made in the daylight. But during the setting of the net on this first tow, Matt observed the net had a tangle as a few floats on the head rope became tangled  with the sweep and footrope on one wing. Matt waited until the last moment when he was absolutely sure that the deck crew had not noticed this obvious screw up and the doors were about to be set, before he pointed out the problem, at which the net was hauled back aboard enough to straighten it out. When a float becomes stuck between the sweep and the headrope it rarely comes out by itself, the resulting tangle will cause the sweep to lift off the bottom and the headrope to close to the sweep. Depending on where the tangle occurs it  will have varying degrees of  effect upon the tow from serious to  disastrous. A tangle close to the wing end would not be as bad as a tangle where  a float in the center of the net became entangled with the roller gear. 

A tangle there would shut the whole net and result in a virtual zero catch for that tow, while a tangle near a wing end would only effect one wing, and the net would still fish but at a reduced efficiency. I must point out that due to the what I consider to be the long length between the hangings of the footrope and the sweep [ a stated 24 inches] this tangle up is probably a common occurrence as this space is so large that when the net is being set out and both the headrope and the sweep are near the surface, the floats find there way into a hole and if not noticed rarely come out until they are manually pulled out by a crewman who should notice them. This isnít a problem that is limited only to this net or to the Albatross, this problem is a common occurrence with many nets, especially large mesh nets where the floats will tangle in the wing mesh itself. This is a basic problem that fishermen always look out for and is almost always detected before the net is set, if it is not noticed the finger of blame gets pointed to someone when the net comes back screwed up and the tow was wasted.

We made our first filmed  tow off of Long Island in about 70 feet of water and it was decided that because of poor visibility we should haul back and try deeper waters where visibility might be better. We then made a  series of tows of  thirty to forty minutes each during the day in various depths of between ten and  thirty nine fathoms. During each tow we would start by towing the wires even for  5 to 10 minutes to observe the netís  behavior under normal conditions and watch the behavior of the fish as they entered the nets fishing circle, and swam with the net, until they either tired and fell back into the net, just swam away somewhere, or were either run over by the rollers, or escaped under the cookie sweep which at most times was a few inches off the bottom  because of the large difference in size between the rollers in the center of the net [ 16 inches] and the cookies  that are on the wings sweep which are only 4 inches high. This is about a 6 inch difference at the corner where the cookies meet the rollers and would gradually lessen as the sweep approached the wing end and the ground gear. It appeared to us that  about half of each wing was not touching bottom during normal operation of the net, with the cables at equal lengths. It should be noted that at no time was visibility  clear enough to see the end of the wings  and that size and possibly distances were distorted to some extent.

The most common species observed were dogfish and loligo squid  but the tows were tripped overboard so actual catch was unknown but minimal. After the initial even towing of the cables, the wires were then offset by two feet by letting out two feet of wire on one side. While the wire was being let out, the camera showed  a shift in the center of the net as  the wing on the side that was being let out  gradually shifted back. The wing that remained in its position showed a shifting in the position of the rollers, as they started to cock sideways a little, and created a larger dust cloud. The twine near this corner showed slight folding as the net started to distort.

After a number of minutes of observations the net would then be let out another two feet for an offset total of four feet. Once again you could visibly watch the wing shift back as now the center of the net that normally goes through the water in a  U shape  started to take on the characteristics of an L. The twine on the slacked back wing showed a slight bowing  effect while the  stable wingís twine showed increased folding and the rollers were almost sideways and plowing heavily through the bottom creating a large dust cloud. The slacked back wing was lifting off the bottom more then previously and  showed  more sensitivity to bumps  on the bottom or waves on the surface.

At a six foot offset the nets distortion was substantial and we all felt its fishing efficiency was substantially compromised . The slacked back wing was  having a hard time making bottom contact, and the twine was  creating a half tunnel effect. On the stable wing the rollers were dramatically plowing through the bottom trailing a large cloud of dust, and the twine showed even further folding and distortion. The clouds of dust that were picked up by the rollers and wings were very informative in showing how the net was pulling through the water as the angle of the clouds would change as the net changed shape. The dust clouds on the slacked back wing were flowing straight back behind the  rollers and cookies while on the stable, forward  towing wing, the clouds were flowing  back but were coming off of the rollers from the side of them as they plowed sideways across the bottom.

At the 12 foot setback the results would have to be considered catastrophic. The  slacked back wing was at a right angle to the  other wing creating an L shape as the net towed through the bottom. The twine on the slacked back wing was bowed in the half tunnel effect, and probably was now more of a gill net then a trawl net. Bottom contact  was severely  impacted on this wing and could be described as minimal .  Major plowing was taking place to the rollers and the cookies on the stable, leading wing. The folds and distortion of  twine on this wing increased even further. Only the dumbest [or unluckiest] fish in the ocean would be caught by a net this distorted. 

After observing the nets reaction through these changes in wire setbacks on one side we would then slack back the wire on the other side in the same manner. The results were the same, as the wire offset increased, so did the nets distortion. The  gear would then be hauled back and we would try a different depth. An observation was made that as we fished in deeper water it seems that the door that we believe to be working improperly worked better as we got deeper.  The sensors that were placed on the doors showed little change in the spread of the doors, but that didnít mean that the net was still being spread, the sensor is  measuring the distance between the doors, and as the one side was slacked back the distance between the doors stayed the same, but the door itself was falling back behind the other door and the spread of the net was being reduced . A flume tank would prove that effect, as would some  not so simple to me math equations. We all strongly believe the doors should be changed and the pair that were being used should be thrown out.  There was a minimal amount of fish caught during these tows the first day and they were tripped overboard.

On the second day we wanted to see if we could find some Codfish to see if we could  catch them and to see if we could discern any change in our catching ability as we let out wire in the 2, 4, 6, and 12 foot setbacks.  We made two tows in the Nantucket lightship area, which didnít produce any cod, but did result in a fifteen hundred pound  tow of mostly dogfish and a few loligo squid.

The same observations were noted as the day before to the net as the wire was let out, and we got to observe the net's effect on dogfish. We watched quite a few dogfish get run over by the rollers and go under the center of the net. When the net was being towed evenly through the water the dogfish, and most other fish evident gravitated to the center of the net. As the net was slacked back and the net lost shape the dogfish moved away from the center and slightly towards  the slacked back wing. The most interesting observation made the second day, at least in my mind was the filming of the netís  behavior as we towed into 4 to 6 foot seas created by northeastery winds of 15 to 20 knots. With the wires even as the ship came up and then down in between swells the whole net would lift off  of the bottom and then come back down a number of feet  further ahead. I compare it to a motorcycle  jumping over  a  series  of bumps.

Bottom contact in rough weather appears by this video to be seriously compromised   which would definitely effect catch rates.  Fish that are swimming in front of the center sweep get leapfrogged over as the net leaves the bottom and comes down many feet ahead of them. Much of this problem is caused by the excessive speed at which the trawl survey nets are towed. If they were towed at ,say, 3 knots, instead of 3.8  the net would probably always remain on the bottom except in the roughest of weather. Of course this would only be true with a net that tends bottom properly, and we all felt that because of the inherent flaw in the sweep design of this net that bottom contact would  always be poor no matter what the conditions. The only way to improve bottom contact with this net is to change the size of  some of the rollers so that there is a gradual change from the 16 inch rollers to the four inch cookies. But the best way to change this net would be  unhook the shackles that connect the wings to the bridles, remove the tripper rope, and replace the whole net with a newer design net that is more adept at doing the job the trawl survey requires of it. The old net could then be retired to an  antique fishing museum where it belongs, and the doors should go with it.

The crew of the Albatross acted at all times in  a completely professional way, and showed a real dedication to their jobs and pride in their work. I donít envy them when  you realize that they go out for twelve days, come  back to port for two, and then are right back out again for another twelve , until the trawl surveys are done. You couldnít pay me enough money to spend that much time at sea away from home and family. They do have a great selection of movies and an excellent cook, we all looked forward to our meals, our thanks to all on the Albatross for their hospitality. And a special thanks to Russell Brown, and Henry Milliken for their grace under pressure, and willingness to keep an open mind to our observations.