Finback chevron patterns used for identification

   

DOLPHIN FLEET FINBACK WHALE SIGHTINGS SUMMARY FOR 2009

John C. Conlon

Our 2009 whale watch season has come to end and we are in late autumn entering winter. Whale watching is on hold until next spring but autumn offers plenty of work time: data analysis in particular. So, here are some thoughts on fin whales for the 2009 season. It was an overall different kind of year for balaenopterid sightings. Fin whale sightings were down from last year: though last year was certainly a great year for fin whales locally. As the fin whale sightings dropped this year so did the number of minke whale sightings though to a greater degree. I was impressed by the small number of minke whales seen this year. I was also surprised by the sighting of a sei whale on September 7th. Unlike minkes we very rarely see sei whales while whale watching. (See our Dolphin Fleet Naturalist's Notebook (5 to 12 September, 2009) for a more complete review of this sei whale sighting.)

Looking more closely at fin whales for the year there are five issues discussed through this report: Allied Whale analysis of our 2006 data; two dead, stranded fin whales from early in the year; analysis of our 2009 data from the perspectives of spatial distribution and individual identification; photographic data collection; and, noteworthy anecdotes from the season.

Robin Sewall of Allied Whale sent back the individual identification analysis for 2006; the matching between the 2006 Dolphin Fleet Fin Whale data and the Allied Whale Western North Atlantic Fin Whale Catalog. Boomerang, Braid, Canopener, Furrow, Goatdance, Hindpaw, Ladders, Loon, Sash, Scorpion, Shark, and Trax have been matched to the Allied Whale catalog. Our “Boomerang” was previously named “Johnny Depp” and first photographed off Mount Desert Rock in 2004. Our “Sash” was previously named “Trigger” and first photographed off Mount Desert Rock in 1987. These names are adjusted in our Dolphin Fleet catalog to match the Allied Whale names. A match was also made between two photos (not particularly good) of DF 06 049 and Allied Whale's FWC 0309. This DF 06 049 example, with a not good photo, underscores the importance of getting photographs of fin whales even if they are at difficult angles or distances. The life history information that Robin has sent has also been incorporated into the onboard catalogs. The life histories include previous Southwestern Gulf of Maine sightings as well as sightings from other locations between New York and Maine. I am looking forward to more analysis coming back from Allied Whale as their work continues. Robin has expressed her appreciation for the work that we have sent to Allied Whale.

We had two Fin Whales come ashore on lower Cape Cod this year. The first was in early February on Dyer Prince Beach in Eastham. I made a visit to this animal on a morning so frigidly windy and cold it reminded me of my early morning walks in northern Canada while working with polar bears. The wind took my breath. This 40 foot male was alive as it stranded but died shortly thereafter. At this length the animal would have been a bit over one year in age. The second dead fin whale was found floating in the middle of Cape Cod Bay in late May. Strong southwest wind pushed the animal onto Herring Cove Beach in Provincetown by late afternoon. I visited this animal several times over the first days it lay on the beach in beautiful early summer weather. This 50 foot male had been dead for some short time before landing on the beach. At 50 feet this animal was a juvenile of about two and a half years old.

I was unable to match either individual to our Dolphin Fleet catalog. I mention this in this report because in each previous year-end Dolphin Fleet Fin Whale report I've discussed problems associated with photo-documentation of mother / calf pairs. I was unable to determine if these were unknown individuals or if they were solely not matchable to photos on record.

In a 1986 report published in the Journal of Mammalogy, entitled, Disease of the Common Fin Whale (Balaenoptera physalus): Crassicaudiosis of the Urinary System, Richard Lambertsen, discussed the significance of the nematode worm, Crassicauda boopis, to fin whales. He estimated this one meter-long nematode to be present in 90 to 95 percent of the animals in the Northeast Atlantic population of fin whales that he studied.

Lambertsen examined an infected unweaned calf and suggests a likely manner of initial infection is for calves to ingest crassicaud larvae present in mothers' urine if she urinates while she is nursing. Ingested urine while nursing would be an easy infestation route for the parasitic larvae given the closeness of the urinary and mammary openings. If either gender urinates during feeding bouts the larvae could just as easily be ingested during the feeding process.

Lambertsen suggests that once the larvae are ingested they make their way from the gut through arteries to the aorta and then into farther blood circulation. Larvae eventually make their way to the kidneys and renal ducts. Lambertsen suggests most crassicaud infections would not be lethal given the high rate of incidence in his study, however, in some cases renal ducts could be sufficiently blocked to lead to renal failure and ultimately death. Lambertsen further suggests, with evidence of depressed red and white blood cell counts, that anemia and blood loss due to heavy crassicaud infestation could compound other health problems that a fin whale might have.

In a 2001 report published in Marine Mammal Science, entitled Collisions Between Ships and Whales, Laist et al., emphasized collisions between ships and fin whales. The authors state that of the “11 species of great whales” studied “fin whales (Balaenoptera physalus) were hit most frequently”. They later state the collision rate with fin whales to be between 20 and 33.7 percent of the total collisions varying with the area studied. Collisions with streamlined bodied balaenopterid whales (blue, fin and sei) were primarily bow strikes while collisions with broader proportioned whale species (right, humpback and sperm) were primarily propeller strikes.

These authors examined collision records beginning in 1885 through 1998 though they clearly state that records prior to 1951 are rare perhaps partly due to overall depressed whale numbers resulting from large scale commercial hunting. In those 1885 to 1950 cases (15 struck whales) only four were identified to species. None were identified as fin whales though given the post 1951 results some percentage of those pre-1950 strikes were likely fin whales.

Whales are certainly aware of what is happening in their surrounding environment. So the question arises as to how these collisions occur? Possible explanations are that whales could be resting in the path of the approaching ship or they may simply misjudge the distance and speed of an approaching vessel. The authors state that injuries to balaenopterid whales are often blunt trauma injuries to the skull, jaws, vertebrae, and heavy bruising to internal organs. All of these injuries can potentially have little visible external damage while still being lethal.

I summarize these two reports here in relation to the necropsies done on the two dead fin whales to come ashore on the Lower Cape this year because exact causes of death are difficult to determine. Parasite infestations and evidence of boat strikes are typically considered. In the case of the February fin whale Michael Moore, a veterinarian working with the International Fund for Animal Welfare (IFAW), reported to the Cape Cod Times that it was likely the animal had the kidney worms but it was not likely to be the cause of death. This agrees with Lambertsen's comments that crassicaud nematodes are not typically lethal. In the case of the May fin whale C.T. Harry (IFAW) said that this animal was more decayed internally than its overall good external appearance indicated. There were no worms in this animal but there was sub-blubber bruising though no deeper bone bruising. In short it is difficult to say why these animals died.

With the help of Dolphin Fleet captains and field guides we collected some 506 data lines on fin whales this year. 171 usable photo ID shots came from 82 data lines with accompanying photographs. Between April 11 th and May 31 st all photographed fin whale sightings were from the northeastern portion of Cape Cod Bay into southern Race Point Channel. June sightings were primarily from Race Point Channel and southeastern Stellwagen Bank. July photos were again primarily Race Point Channel and to a lesser extent southeastern Stellwagen. The first half of August gave us 10 photo data sets from Race Point Channel. The second half of August and the first half of September gave us one data line with photos for each period. We did not have another fin whale sighting with accompanying photos for the remainder of the season. Thirty-two of the 82 photo ID lines came from northeastern Cape Cod Bay while 41 other photo data lines came from Race Point Channel. Southern Stellwagen Bank and Race Point Channel are generally the areas most heavily used by fin whales within our whale watch range. This year, however, we spent very little time on the southwestern part of the bank.

Comparing this year’s fin whale sightings to 2008 distribution the 82 photo ID data lines of 2009 is just over half the 150 photo ID data lines from 2008. This gave us 44 individuals for 2009 compared to 57 for 2008. Between mid-April and May’s end all 2009 fin whale photos came from northeastern Cape Cod Bay and Race Point Channel. There were no photos from Cape Cod Bay after the end of May this year. Beginning in early June distribution shifted from Cape Cod Bay out into Race Point Channel and toward the north and northeast. This is consistent with 2008. By late July our limited number of photos was confined to Race Point Channel. As previously stated we had in late August and early September one photo data set each and none from then on through the 2009 season’s end. During those same last two months in 2008 we only 4 data lines with photos. (2007 had 65 data lines with photos during the same time period.)

The total of known individuals for 2009 was 40. Named individuals IDed this year: Amp, Belt, Breaker, Cyrano, Dahlia, Dali, Darth, Drumlin, Hook, Johnny Depp, Lenin, Loon, Mottle, Nightcap, Pyramid, Rila, Ruby, Scorpion, Sagitta, Skeg, Spike, Steller, Sunspot (with her second Dolphin Fleet recorded calf), Thunder, and Trout. We had one non-data set of photos of Shark. Unnamed though IDed individuals are: 07 005, 07 039 (Scorpion's 2007 calf), 07 058, 07 120, 07 164, 07 227, 08 011, 08 015, 08 022, 08 024, 08 031, 08 039, 08 122 and 08 142. We had only one sighting of Sunspot and her 2009 calf. Single sightings, questionable focus and bad angle, sometimes two or all three problems, are present in a mother / calf sighting. Consequently, mother / calf pairs are quite challenging to work with. Fortunately this year’s single Sunspot and calf sighting was well photographed.

 

DF 09 055

We had four identified new individual fin whales (not tied to previous sighting records). (DF 09 055 photograph above.) Sunspot’s 2009 calf makes a fifth new individual. Combined this brings our 2009 total to 44 individuals including the calf. Many individuals had multiple records. Other individuals had few or even only one record for the season. 88.6% of the year’s fin whales have previous sighting records while only 9% were new this year. (Obviously the calf has no previous record.) We also have a minimum of 4 unmatchable photo sets (sections of backs, for example, that have no dorsal fin or chevron markings). All of named individuals and unnamed 07 XXX individuals are in the Fin Whale catalogs on the boats. Their accompanying life history sheets are up to date as of 2009.

Alacran, 2007 calf of Scorpion

Given my ongoing concerns regarding mother / calf pair documentation I'm particularly pleased with several sightings. This year’s photos of Scorpion's second known calf, Alacran (DF 07 039), were great. Scorpion was our first known fin whale with two recorded calves. Scorpion’s previous known calf was born in 1985. We also had sightings of DF 07 005 born to Cormorant in 2007, DF 08 031 born to DF 08 030 in 2008, and DF 08 039 born to DF 07 164 in 2007. I'm also very pleased with this year’s documentation of Sunspot with her second known calf. This is our first record of a female fin whale with calves from two consecutive breeding cycles. After four years of work our Dolphin Fleet Fin Whale Catalog now has ten recorded fin whale calves (including Sunspot’s 2009 calf). Great work, everybody!

Some questions have come from several guides regarding fin whale photographic data collection. Each year passengers send me fin whale photos and those passengers ask the same questions. So, here are some thoughts to help passengers in the field. We all know that fin whales are more difficult to photograph than are humpbacks. We can not subconsciously expect them to act similarly. Yet, if we don't use the camera there are no photos. Ideally we want the most complete set of right side AND left side shots possible. This includes chevron and dorsal fin. Left side shots are EQUALLY as valid as right side shots especially of the dorsal fin. Indeed we are short on good left side photos including left side dorsal fins. If possible shoot everything possible. A scar or deformity should not preclude shooting the dorsal fin when workable.

An animal does not have to be right next to the boat for effective ID shots. Fin whales are rarely as close as humpbacks. Given digital and computer capabilities we are often able to pull good and reliable IDs from more distant whales. Several boat lengths is workable and more distant is even workable if the focus is good. Fin whales are difficult to match in terms of chevron patterns when dealing with different ambient light conditions. It is thus important to get good photos. One reason… We have already eliminated a couple duplicate individuals that were thought to be two different individuals. With more and better photos they turned out to be the same individual. Good clear shots are also important for our website development. And the year's final report always includes the year’s most noteworthy photo.

The second question, or more accurately, I should say comment(s) are regarding the catalogs on the boats. We are trying to do better with the dorsal fin shots because dorsal fins are easier than chevron patterns to use in the field. Dorsal fin shots are thus enlarged as much as possible without creating (too much) distortion. If you can get good dorsal fin shots the field IDs will be easier for those field guides and passengers who are interested. A reasonably clear dorsal fin shot will get you there. I've talked with several guides about making the dorsal fin IDs even easier and will work on those ideas for catalog development in the future. So thank you to those of you, especially field guides, who have given your feedback.

Sunspot and her 2009 calf

Deciding who to acknowledge for the year’s best photo(s) was VERY difficult. The two choices were both of photo sets that were not only great photos but also great from a documentation perspective. Ultimately the two photo sets were a draw between Mike Bertoldi, and, umm, Mike Bertoldi! In fact I decided the photos were a draw before I knew who shot the pictures! So, the Mike and Mike realization came as a surprise! At the head of this report is a series of left and right side shots of Lenin that Mike took on May 22 nd. Take a look at the shadow of the passing gull in the upper middle photo. We first recorded Lenin in 2006. Lenin is quite difficult to ID if photographed from angles other than perpendicular to the dorsal fin. And, at the head of this paragraph is a photo that Mike took on the May 20 th of Sunspot with her second known calf. This was the ONLY set of fin whale mother calf photos we have for the year.

Lastly, I'd like to say THANK YOU to all the field guides and captains for their work! Good photos came in and many of those animals are known to us. My sincerest gratitude is due to those who have contributed to this year’s research. First, thank you to Dr. Carole Carlson and her entire team of field guides (Irene, Nancy, Kate, Sarah, Owen, Beth, Therese, Gwen, Liz, Mark, Mike, Dennis and Peter). Carole’s team also includes interns from local school systems, and volunteers from the Cape Cod Museum of Natural History. This team collected the fin whale data. None of the data collection was possible without the Dolphin Fleet captains: Dennis, John, Todd, Pete, Brian, Scott, Mark, and Steve whose skill and patience are very much appreciated by both our research staff and passengers. Thank you to Sarah Fortune and Kate Longley for editing the season’s fin whale notes into our Naturalist’s Notebook. Thank you to Anna Jankowicz-Conlon for data entry assistance and photographic editing of our fin whale catalog. Thank you again to Dr. Carole Carlson, our Director of Education and Research, for overseeing all the written and photographic data entry and processing into usable form. Thank you to Steve Milliken and the Dolphin Fleet for the steady encouragement and support to make this research on fin whales, indeed, our entire research and education program, a reality. It is truly an honor to work with and for people who are genuinely concerned. And finally, THANK YOU, THANK YOU to all of you, our Dolphin Fleet passengers. Your willingness to share time with us on our trips along with your encouragement, enthusiasm, and support is a significant reason that we at the Dolphin Fleet are able to accomplish so much. Join us again in 2010!

 

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