Lithodes Aequispinus Research Articles

On feeding of deep-sea crabs on the continental slope of northwestern Kamchatka

Mean index of gastrointestinal tract fullness for golden king crab Lithodes aequispinus is 15.5 ‱. Detritus occurs in 40.5 % of the cases, so it is a common food for this crab, Polychaeta, Ophiuroidea and Decapoda are 33.2 %, 32.1 % and 15.4 % of its ration, respectively, whereas Mollusca are only 11.5 % of the ration weight, despite of frequent occurrence. Triangle tanner crab Chionoecetes angulatus has the mean index of fullness 20.9 ‱, Polychaeta and Mollusca are two main components of its ration (31.4 % and 27.3 %, respectively) and Decapoda and Pisces are the secondary components (13.9 % and 12.2 %); detritus occurs in 11.2 % of the cases. Cannibalism is observed incidentally for the latter species.

Data weighting for tagging data in integrated size-structured models

Increasingly, stock assessments for hard-to-age species such as crabs, prawns, rock lobsters, and abalone are being based on integrated size-structured population dynamics models that are fit to a variety of data sources. These data sources include tagging data to inform growth. Diagnostic statistics and plots have been developed to explore how well integrated population models fit the data types typically used for assessment purposes (index data, size- and age-compositions, and conditional age-at-length data). However, such statistics and plots are not available for tagging data, when these data are used to estimate growth. This paper outlines two diagnostic statistics that can be used to evaluate fits to tagging data, and develops a method based on ‘Francis weighting’ for weighting tagging data in integrated models. For illustration, the methods are applied to Aleutian Islands golden king crab (Lithodes aequispinus) in Alaska, and tiger prawns (Penaeus semisulcatus and P. esculentus) in Australia's Northern Prawn Fishery. Some degree of growth model mis-specification was revealed for P. semisulcatus, and there were conflicts in the data for the tiger prawns. The standard errors for the estimates of mature male biomass for golden king crab were larger when the tagging data were downweighted based on the proposed weighting method. This serves to emphasise that assessments and their interpretations can be impacted by how tagging data are weighted.

Embryo development in golden king crab (Lithodes aequispinus)

Embryo development in golden king crab (Lithodes aequispinus)

Two new cryptic and sympatric species of the king crab parasite Briarosaccus (Cirripedia: Rhizocephala) in the North Pacific.

Rhizocephalan barnacles have been reported to parasitize a wide range of king crab species (Lithodidae). So far all these parasites have been assigned to a single species, Briarosaccus callosus Boschma, 1930, which is assumed to have a global distribution. Here we investigate Briarosaccus specimens from three different king crab hosts from the fjord systems of Southeastern Alaska: Lithodes aequispinus Benedict, 1895, Paralithodes camtschaticus (Tilesius, 1815), and Paralithodes platypus (Brandt, 1850). Using molecular markers and by morphological comparison we show that Briarosaccus specimens from these three commercial exploited king crabs are in fact morphologically distinct from B. callosus, and further represent two separate species which we describe. The two new species, Briarosaccus auratum n. sp. and B. regalis n. sp., are cryptic by morphological means and were identified as distinct species by the use of genetic markers (COI and 16S). They occur sympatrically, yet no overlap in king crab hosts occurs, with B. auratum n. sp. only found on L. aequispinus, and B. regalis n. sp. as parasite of the two Paralithodes hosts.

Estimation of size–transition matrices with and without molt probability for Alaska golden king crab using tag–recapture data

Size-structured population dynamics models are used for stock assessments of hard to age invertebrate species, such as crabs, and size–transition matrices play an important role in modeling growth in those models. Crabs grow by molting and then incrementing in size. Therefore, the size–transition matrix should ideally contain sub-models for the probability of molt and the growth increment. Size–transition matrices were estimated in an integrated model setting, which included tagging data. Various models, including those that explicitly model molt probability and that include the molt implicitly in the size–transition model, were applied to data for golden king crab (Lithodes aequispinus) in the eastern Aleutian Islands region. Several diagnostic statistics (e.g., covariance matrix, likelihood, AIC, mean growth increment metric, sensitivity of estimates of mature male biomass, and the fits to the tag recapture, catch-per-unit effort, and length frequency data) were used to investigate the implications of the way growth was modeled. Overall, the fit of the integrated model that included the molt probability sub-model was better than that of the model that did not include this sub-model. However, the trends in key stock assessment outputs did not differ markedly between approaches for modeling growth even though the estimates of the size–transition matrices differed.

Egg Deposition and Development of Eggs and Larvae of Bigmouth Sculpin (Hemitripterus bolini)

The Bigmouth Sculpin, Hemitripterus bolini, is a cottoid fish in the family Hemitripteridae found throughout the Bering Sea and Gulf of Alaska to British Columbia, Canada, and northern California. Hemitripterids have internal gametic association with external fertilization as their mode of reproduction. With this strategy, spermatozoa are stored in the micropyle of eggs within the ovary after gamete transfer to the female and eggs are not fertilized until immersed in seawater. Female H. bolini deposit their eggs into at least 4 species of sponges. We collected eggs from Barrel Sponge (Halichondria lambei), Clay-Pipe Sponge (Aphrocallistes vastus), Boot Sponge (Acanthascus dawsoni), and Tree Sponge (Mycale loveni) in the Gulf of Alaska and Bering Sea. In contrast to its congeners, there has been little research on H. bolini, particularly any focusing on aspects of early life history stages. In this study, we describe the development of H. bolini eggs and larvae from newly-hatched stages to juveniles, and include general observations of osteology. The descriptions of larvae and juveniles are based on examination of 32 specimens, 5 of which were differentially cleared and stained to examine osteological development. Larvae hatch at a large size (13 to 14 mm SL) in an advanced stage of development. Postflexion occurs at approximately 20 mm SL, and transformation to the juvenile stage begins at about 31 mm SL. Larvae are heavily pigmented through late flexion, when pigmentation becomes reduced. Postflexion larvae and juveniles are also heavily pigmented. Ossification of most skeletal elements does not occur until postflexion. The description will help distinguish H. bolini from other hemitripterids and sympatric larvae of the family Agonidae that are similar in appearance but generally smaller and more slender-bodied at all developmental stages. The behavior of egg deposition in sponges, in conjunction with the use of sponges by other fishes such as juvenile rockfish and invertebrates such as Golden King Crabs (Lithodes aequispina) as refuge habitat, suggests that sponge grounds may provide essential fish habitat for H. bolini and other species.

A review of worldwide fisheries for lithodid crabs (Decapoda: Anomura: Lithodidae) and their fluctuations

Lithodid crab isheries began before 1900 in Japan and spread across the North Pacific Ocean by 1940. Fisheries targeted red king crab (Paralithodes camtschaticus) with lesser amounts of blue king crab (P. platypus) and brown king crab (P. brevipes). Paralithodes spp., especially red king crabs, have always dominated lithodid fisheries. Golden king crab (Lithodes aequispinus) became important in North Pacific Ocean waters after major declines in red king crab fisheries in the early 1980's. Southern king crab (Lithodes santolla) are fished in southern South America along with softshell red crab (Paralomis granulosa). These five species accounted for more than 89% of lithodid landings for 1984-2003. World lithodid landings peaked at 150,100 metric tons (t) in 1966 after development in pre-World War II Asia and rapid post-1950 expansion in Alaska and Asia. The world lithodid landings fell to 60,540 t in 1973 but rebounded to 104,970 t in 1980, due to abundant eastern Bering Sea red king crab stocks. Eastern Bering Sea and Gulf of Alaska red king crab stocks soon collapsed, and landings fell to a low of 40,920 t in 1983. The world Iithodid landings reached 81,390 t in 1997 with increased Russian landings, but have declined sharply to only 32,610 t. In the 1960's, Russian scientists successfully introduced red king crabs to the Atlantic Ocean and resultant fisheries currently provide 9% of world lithodid landings. Elsewhere , Paralithodes spp. landings trend downward, white other lithodid species are stable or increasing.

Effects of the Briarosaccus callosus Infestation on the Commercial Golden King Crab Lithodes aequispina

Commercial crab populations off the Kamchatka coasts are infested to a considerable degree by the rhizocephalan parasite Briarosaccus callosus: of 769 Lithodes aequispina males examined, 43 (5.7%) were parasitized. Infestations result in the feminization of the crabs, a significant decrease in the cheliped length, and a significant decrease in the carapace length and width. We suggest that commercial selection of healthy males, and the returning of unsuitable crabs, including infested ones, back into the sea, results in an increase of the proportion of infested crabs in the population, their elimination from reproduction, and, eventually, the gradual degradation of a whole population. To minimize as far as possible the negative effects of commercial crab harvesting, all infested crab specimens caught must be destroyed, either aboard or elsewhere, instead of throwing them back into the sea.

Development of microsatellite loci in red king crab (Paralithodes camtschaticus)

AbstractPolymerase chain reaction (PCR) primers for three trinucleotide and three tetranucleotide microsatellite loci were developed for red king crab (Paralithodes camtschaticus) to aid in studies of genetic population structure in Alaskan waters. Number of alleles ranged from six to 18 alleles (N = 562), and locus heterozygosities ranged from 0.505 to 0.839. Six primers were cross amplified with golden king crab (Lithodes aequispinus); five primers with blue king crab (P. platypus); and one primer with the splendid hermit crab (Labidochirus splendescens), the ‘missing link’ between pagurid and lithodid crabs. No cross amplification occurred with Tanner crab (Chionoecetes bairdi) or Aleutian hermit crab (Pagurus aleuticus).

Size of Maturity in Male Golden King Crab, Lithodes Aequispinus (Anomura: Lithodidae)

Abstract Typically ≥90% of the eggs in clutches fertilized by hardshell Prince William Sound Lithodes aequispinus males ≥107 mm carapace length initiated division. Golden king crab males with only one chela and those with post-molt carapaces ≥11 days old were effective parents. Some test males had exclusive access to three ripe females. Their first and second mates all produced viable clutches with 81–100% of eggs exhibiting development. Not all males induced a third female to ovulate. The percentage of eggs initiating division in the clutches of their third potential female mates ranged from 56 to 100%.

Phototaxis and Geotaxis of Light-Adapted Zoeae of the Golden King Crab Lithodes aequispinus (Anomura: Lithodidae) in the Laboratory

Phototaxis and Geotaxis of Light-Adapted Zoeae of the Golden King Crab Lithodes aequispinus (Anomura: Lithodidae) in the Laboratory

Development of Larvae of the Golden King Crab Lithodes Aequispinus (Anomura: Lithodidae) Reared at Different Temperatures

Unfed lecithotrophic larvae of the golden king crab Lithodes aequispinus were reared at 3, 6, and 9°C in darkness and 33-34 ppt salinity. This study was done to improve our understanding of larval development time and the ability of the larvae to survive under different seasonal thermal conditions. The survival rates and intermolt duration was observed for the first zoeal molt (ZI), second molt (ZII), third molt (ZIII), and glaucothoe (G). The duration from hatching to the start of the first nonlarval stage (crab 1) averaged 148, 94, and 75 days at 3, 6, and 9°C, respectively. Development rate for ZI to Crab I versus the rearing temperature was described by the equation: Development period (days) = -35.82 (Rearing Temperature °C) + 1.96 (°C2) + 238.6; r2 = 0.99. Regardless of stage, every degree increase in temperature reduced the length of the development period by approximately 9%. Survival rates of ZI larvae were typically >97% regardless of temperature. By the completion of the ZII molt 83-87% were still surviving. Survival rates to the end of the ZIII molt at 3° and 6°C were 77% and 75%, but only 65% at 9°C. Within stages there was no significant difference in survival rates for ZI, ZII, or ZIII at the 3 test temperatures. The survival rate through the glaucothoe stage was 47% and 51% for larvae reared at 3° and 6°C, respectively, while only 16% of those at 9°C survived to Crab I. There was no significant difference in the percentage of glaucothoe surviving at 3, 6, and 9°C.

Crustacean resources are vulnerable to serial depletion – the multifaceted decline of crab and shrimp fisheries in the Greater Gulf of Alaska

The seas around Alaska support (or have supported) some of the most commercially significant crustacean stocks in the world, spread over an overwhelming array of extensive and diverse coastal and open shelf areas. Major resources include three species of king crab (Paralithodes spp. and Lithodes aequispina), Tanner and snow crab (Chionoecetes spp.), Dungeness crab (Cancer magister), and five species of pandalid shrimp (Pandalus spp. and Pandalopsis dispar). Excluding the Bering Sea, the resources from the Greater Gulf of Alaska (ranging from the Aleutian Chain to the state's south-eastern panhandle contiguous with British Columbia) supported rapid expansion of several crab and shrimp fisheries during the 20 year period 1960–1980. Since then, most of those fisheries have collapsed. While some of the stock declines have been well documented and discussed (most prominently the ‘dethroning’ of red king crab on the shelf around Kodiak Island), it has been less apparent that the demise of Alaskan crustace an stocks is a process on a much larger scale, and is still unfolding. Here we examine trends in catch, recruitment and abundance (when possible) and discuss existing evidence of overfishing and management options. We emphasize the importance of recognizing the multi-scale spatial structure of crustacean stocks, and suggest the need to consider spatially explicit strategies, particularly the creation of reproductive refugia

LECITHOTROPHIC DEVELOPMENT OF THE GOLDEN KING CRAB LITHODES AEQUISPINUS (ANOMURA: LITHODIDAE)

ABSTRACT Larvae of the golden king crab Lithodes aequispinus were reared in individual chambers in the laboratory from hatching to the first crab stage (C1). The experiment included 2 treatments: 1 group was fed live nauplii of Artemia daily, while the other group was unfed. A total of 4 molts were observed for all larvae from hatching to Cl. One larval stage, either zoea III or zoea IV, was skipped by all larvae. No significant difference existed for the duration of development of each stage between fed and unfed treatments. The mean durations were ZI (ZI = zoeal stage I, ZII = zoeal stage II, etc.) = 6.6 days (±0.71 SD), ZIIa (molted to ZIII) = 7.0 d (±0.65 SD), ZIIb (molted to ZIV) = 8.8 d (±0.95 SD), ZIII (skipped ZIV) = 12.0 d (±1.33 SD), ZIV (skipped ZIII) = 9.3 d (± 1.63 SD), and glaucothoe = 41.3 d (±2.65 SD). The total larval duration was approximately 67 d. The survival rate of the fed group was significantly lower than that of the unfed group. Seventeen percent of unfed larvae developed to Cl, but only 0.7% of fed larvae did so. The longest duration of survival from hatching was 191 d for an unfed crab. The dry weights of unfed larvae decreased 10% from hatching to Cl. Our results indicate that the larval development of the golden king crab is fully lecithotrophic, i.e., larvae can successfully develop to juvenile crabs without eating.

Hemolymph responses of Alaskan king crabs to rhizocephalan parasitism

Hemolymph from three king crab species, red (Paralithodes camtschatica), blue (P. platypus), and golden (Lithodes aequispina), parasitized by the rhizocephalan Briarosaccus callosus was examined for parasite-induced changes. Protein, hemoglobin, hemocyanin, and glucose concentrations, hemocyte counts, pH, osmolality, and hemolymph ion concentrations were measured. Parasite hemolymph was also examined. Effects on host hemolymph were decreased osmolality and sodium and chloride concentrations, and increased protein, hemocyanin, and glucose concentrations. Not all effects occurred in each host species. Correlations existed in some host species between number of externae and sodium and protein concentrations and shell condition. Protein electrophoregrams of parasitized and unparasitized crabs were similar. The red color of parasite hemolymph was due to hemoglobin averaging 5.8 mg/mL. No parasite hemoglobin was found in the host hemolymph. Electrophoregrams of parasite hemolymph from the three host species were similar. Hemocyanin was present in parasite hemolymph from red and golden king crab hosts. No significant difference in hemocyte count existed between parasitized and unparasitized blue king crabs. Red and golden king crabs exhibited a response that could explain their lower rates of parasitism and less frequent multiple infections, while blue king crabs had little defense against the parasite.

Prevalence of the Parasitic Barnacle Briarosaccus callosus on King Crabs of Southeastern Alaska

The rhizocephalan barnacle Briarosaccas callosus causes sterilization and reduced growth of red Paralithodes camtschatica, blue P. platypus, and golden Lithodes aequispina king crabs, commercially important species in southeastern Alaska. The prevalence of the parasite (percentage of king crabs infected) was monitored from 1979 through 1985 within a 115-km radius of Juneau. Prevalences were typically less than 1% in commercial landings of legal red and golden king crabs (males only; minimum carapace width 179 mm), but reached 12% in landings of blue king crabs (males of 165 mm minimum carapace width). Annual surveys of commercial red king crab pots, which contain females and sublegal males, usually indicated prevalences of less than 1%, though 50% was reached in exceptional cases. On-board samples from commercial boats that included females and sublegal males confirmed low prevalences (<1%) for red king crabs, but 20% of golden king crabs and 76% of the blue king crabs were parasitized. Within broad temporal and geographic variation, blue king crabs were the most, and red king crabs were the least, heavily parasitized by barnacles of the three host species considered. Prevalences tended to be greater for smaller than for larger hosts, for females than for males among blue and red king crabs, and in turbid than in clear water.

Histopathology and host response in lithodid crabs parasitized by Briarosaccus callosus

Two red (Paralithodes camtschatica) and 26 golden (Lthodes aequispina) king crabs parasitized by the rhzocephalan Briarosaccus callosus were examined microscopically for histopathological effects of and host response to the parasite. Although numerous organs were invaded and tissues displaced, replaced or compacted, there was little necrosis or degeneration of tissues other than gonads. Host response to healthy B. callosus was negliqble, but degenerating rootlets of the parasite elicited heavy hemocytic response in a typical crustacean foreign-body reaction. Boschma (1962) described Briarosaccus callosus and suggested it may be a cosmopolitan parasite of lithodid crabs, reporting it from Lithodes aequispina in the Bering Sea, L. agassizii off southeastern United States, and L. antarcticus and Paralomis granulosa in the Antarctic and sub-Antarctic regions. Subsequently, Boschma & Haynes (1969) reported it from Pardithodes camtschatica in southeastern Alaska. Hawkes et al. (1985a) first reported B. callosus from Paralithodes platypus, again from southeast Alaska. Prevalences of infection have been investigated in blue king crab Paralithodes platypus (Hawkes et al. 1985a, b), red king crab P. camtschatica (Hawkes et al. 1986), and golden king crab Lithodes aequispina, as have gross observations on the effect on growth, reproduction and migratory behavior of parasitized crabs (Sloan 1984, 1985, Bower & Sloan 1985, Hawkes et al. 1986), but heretofore the histopathological effects have been only briefly mentioned (Sparks 1985, Sparks & Morado 1985). MATERIALS AND METHODS Two red king crabs Parahthodes camtschatica with Briarosaccus callosus externa were shipped alive to our laboratory where necropsies were performed and random samples of the major organ systems were O Inter-Research/Printed in F. R. Germany excised, fixed, and processed by standard histotechniques. All other crabs were collected during crab population surveys by the Resource Assessment and Conservation Engineering Division (RACE) of the National Marine Fisheries Service (NMFS) or Alaska Department of Fish and Game (ADF & G). Necropsies were performed aboard ship by personnel of our laboratory, the NMFS Kodiak Laboratory or the ADF&G. The fixed tissues were processed in our laboratory where microscopical observations were made on the histopathological effects of B. callosus and host response to the parasite in parasitized crabs.

Morphology of the Externa of Briarosaccus callosus Boschma (Rhizocephala) and the Relationship with Its Host Lithodes aequispina Benedict (Anomura)

During 3 surveys of fjords in northern British Columbia between October 1983 and July 1984, a total of 707 rhizocephalan parasites (Briarosaccus callosus) on 572 anomuran king crabs (Lithodes aequispina) were examined. Briarosaccus callosus is a large species with extemae varying from 9 to 165 mm in curve length. Lithodes aequispina is probably infected with B. callosus early in life. The extema of B. callosus begin producing clutches of eggs shortly after emergence from the crab host when still small in size (9 to 15 mm in curve length). Each clutch of eggs is deposited into the mantle cavity where the eggs develop into nauplii which are probably extruded by the muscular contractions of the mantle wall. The extema then moults the outer covering and the mantle cavity lining and the entire cycle is repeated. There appears to be no seasonality in B. callosus reproduction and at least 33 cycles may occur during the life of an average sized (curve length of 95 mm) parasite. The majority (96%) of the extemae were attached to the flexible cuticle of the ventral surface of the abdomen and were oriented perpendicular to the long axis of the crab with the opening of the mantle cavity directed towards the crab's left side. Exterae do not appear to prohibit the crab from moulting, thus both host and parasite grow together for what may be the duration of the crab's life. Multiple parasitism may affect the growth of the crab and the extemae but the size of male and female crabs with 1 extema were similar to that of uninfected female crabs. Boschma (1930) described Briarosaccus cal- losus, a rhizocephalan parasite, from a museum specimen of Lithodes agassizii collected at a depth of 494 or 864 m off Florida or North Carolina, U.S.A., in 1886. Briarosaccus callosus has since been recorded world-wide from 7 other ano-

Size at Sexual Maturity and Fecundity of the Fjord-dwelling Golden King Crab Lithodes Aequispina Benedict from Northern British Columbia

ABSTRACT Size at maturity of fjord-dwelling golden king crabs, Lithodes aequispina, from northern British Columbia is 114 mm carapace length (CL) for males, based on chela allometry, and 105.5 mm CL for females, based on the presence of eggs (embryos) or empty egg cases on the pleopod setae. Females carried up to 27,000 eggs. Fecundity (F), measured soon after egg extrusion, increases with carapace length according to: F = – 18,760 + 294 CL. Embryo mortality, from egg extrusion until the appearance of embryonic eyes, decreases from 13% for 110 mm CL females to 8% for 140 mm females. Mean length of external eggs immediately before hatching is 2.4 mm. Based on the size limit at maturity and estimates of growth rate, a minimum commercial size limit of 163 mm CL (=181 mm carapace width, including lateral spines) would protect males for three years after maturity is reached.

Size at Sexual Maturity and Fecundity of the Fjord-dwelling Golden King Crab Lithodes Aequispina Benedict from Northern British Columbia

ABSTRACT Size at maturity of fjord-dwelling golden king crabs, Lithodes aequispina, from northern British Columbia is 114 mm carapace length (CL) for males, based on chela allometry, and 105.5 mm CL for females, based on the presence of "eggs" (embryos) or empty egg cases on the pleopod setae. Females carried up to 27,000 "eggs." Fecundity (F), measured soon after egg extrusion, increases with carapace length according to: F = – 18,760 + 294 CL. Embryo mortality, from egg extrusion until the appearance of embryonic eyes, decreases from 13% for 110 mm CL females to 8% for 140 mm females. Mean length of external "eggs" immediately before hatching is 2.4 mm. Based on the size limit at maturity and estimates of growth rate, a minimum commercial size limit of 163 mm CL (=181 mm carapace width, including lateral spines) would protect males for three years after maturity is reached.